Vocalisations of Northern Quolls, Dasyurus hallucatus, were recorded during staged interactions b... more Vocalisations of Northern Quolls, Dasyurus hallucatus, were recorded during staged interactions between pairs of the same sex and different sexes. Four types of vocalisations were identified: 'hisses', 'sniffs', 'squawks' and 'twitters'. No pure ultrasonic calls were identified, although frequencies of twitters and sniffs extended into the ultrasonic range. All vocalisations were broadband, noisy sounds, with little evidence of harmonic structure or frequency modulation. Vocalisations of D. hallucatus are compared with data for other dasyurid species, and the correlation between frequencies of vocalisations and maximum sensitivity of the brain auditory pathway is discussed.
Concerns have been raised in the scientific community that many teachers do not accept evolution ... more Concerns have been raised in the scientific community that many teachers do not accept evolution as a scientific, testable phenomenon, and this is evident in their teaching. The non-acceptance of evolution theory is often heavily influenced by religious groups that endeavour to eliminate evolution from the curriculum. In South Africa, the inclusion of evolution in the curriculum is a recent event. This study focused on teachers’ views of evolution in relation to their religious affiliations. A questionnaire was developed and was validated by the Biohead–Citizen Project, and was then administered to more than 300 South African teachers and student teachers. Equal numbers of pre-service and in-service teachers were sampled. The groups included equal numbers of biology, English, and generalist teachers at primary school level. The results showed differences between teachers from different religions with regard to their views of evolution. Among teachers who identified as agnostic or at...
African Journal of Research in Mathematics, Science and Technology Education, Apr 2, 2015
Quantitative methods of data analysis usually involve inferential statistics, and are not well kn... more Quantitative methods of data analysis usually involve inferential statistics, and are not well known for their ability to reflect the intricacies of a diverse student population. The South African tertiary education sector is characterised by extreme inequality and diversity. Foundation programmes address issues of inequality of access by providing an opportunity for disadvantaged students with academic potential to enter mainstream degree programmes. Seeking to understand which factors are most influential in enhancing student selection and their performance in a foundation mathematics module, Classification and Regression Tree (CART) analysis is presented as a non-parametric alternative to traditional quantitative research methods. CART, a data-mining technique, is illustrated with reference to two cohorts of students enrolled in the foundation module. The two cohorts had experienced different secondary school curricula. The regression tree to examine students' final mathematics marks illustrated that the primary performance indicators for both cohorts related to the alternative selection criteria, whereas school-level performance was of little consequence. The classification tree showed that passing the module depended on socio-economic, and not academic, indicators, irrespective of school history. The hierarchy of context-dependent influences revealed in the trees illustrated that no single variable can be the basis for a framework for practical and policy responsiveness in a context of such student diversity.
This study investigated pre-and postmating isolation in two karyotypically identical gerbil speci... more This study investigated pre-and postmating isolation in two karyotypically identical gerbil species, Tatera afra and T. brantsii. The species are allopatric and morphologically distinguishable, with no natural hybrids having been reported. Evidence of premating discrimination between conspecifics and heterospecifics was inconclusive. A trent towards more nasal and anogenital sniffing, and less perineal dragging in conspecific than in heterospecific pairings was observed, but differences were statistically significant in only a few pairings. Hybrid litters were produced from six out of 16 heterospecific pairings. 50 % of hybrids died before 5 months of age, and male hybrids were more vulnerable than females. No hybrid pairings have resulted in offspring, but 1 out of 3 backcross pairings between female hybrids and pure-bred males have resulted in a normal litter. Evidence suggests that despite the lack of chromosomal divergence often associated with specialion events in rodents, postmating isolation through hybrid disadvantage and possibly male sterility is operating. Pre-mating isolating mechanisms seem to be poorly developed. Resume.-Chez deux especes de Gerbillides dont le caryotype est identique, Tatera afra et T. brantsii, on a etudie 1'isolement reproductif pre-et postcopulatoire. Ces especes sont allopatriques et morphologiquement distinctes. On n'en connait pas d'hybrides naturels. On n'a pas pu metlre en evidence de preuve concluante d'une discrimination precopulatoire entre individus conspecifiques ou heterospecifiques. Toutefois on a pu observer des tendances plus marquees au flairement nasal et anogenital, et moins marquees au frottement perineal chez des couples conspecifiques que chcz les heterospocifiques, mais les differences n'ont ete statistiquement significatives quc dans quelques couples. Six sur 16 couples heterospecifiques ont produit des portees hybrides. Mais 50 % des hybrides sont morts avant Tage de 5 mois, les hybrides males elant plus vulndrables que les femelies. Aucun couple d'hybrides n'a eu de jeunes, mais Tun des 3 couples de croisements en retour entre femelles hybrides et males de souche pure a produit une portee normale. En depit de absence de divergence chromosomique, sou vent associee ä la speciation chez les rongeurs, Fisolement reproductif postcopulatoire agit en desavantageant l'hybride et probablement en favorisant la sterilite male. Les mecanismes d'isolement precopulatoire semblent tres peu developpes.
Elephant-shrews produce acoustic signals by tapping their hindfcet. Footdrumming is elicited in l... more Elephant-shrews produce acoustic signals by tapping their hindfcet. Footdrumming is elicited in laboratory populations by disturbance and during agonistic encounters. Species-specific patterns of footdrumming have been described for several rodent species. The purpose of the present study was to find out whether footdrumming patterns are species-specific in the five South African Elephantulus species, and if so, whether the evolutionary patterns of development could be determined. Species included in this study were £. edwardii. E. rupestris, E. brachyrhynchus, E. myurus and E. intufi. Footdrummings were recorded and analysed using a sonograph. Footdrums are emitted in a series consisting of one or more bouts, each footdrumming bout being made up of one or more footdrums, usually between 25-50 msec, apart. Each elephant-shrew species has a distinctive pattern of footdrumming. Parameters which differ among species include absence or presence of irregular elements, number of footdrums per bout, number of footdrumming bouts per series and intervals between successive footdrums. Resume.-Les Elephantulus produisent des signaux acoustiques en tapant du pied. La podophonie cst declenchee en laboratoire lorsque les animaux sont perturbes et au cours de rencontres agonistiques. DC la podophonie propre ä chaque espece a etc decrite chez plusieurs rongeurs. Dans cette etude nous nous proposons de rechercher si la podophonie est specifique chez les cinq especes d'Elephantulus d'Afrique du Sud, et dans ce cas, si des Schemas de developpement cvolutif peuvent etre mis en evidence. Les podophones ont ete enregistres et analyses avec un sonographe. Us sont emis en serie d'une ou plusieurs sequences, chaque podophone etant constitue d'un ou plusieurs tapements de pied, espaces en general de 25 ä 50 msec. Chaque espece d 1 Elephantulus a un schema distinct de podophone. Les parametres qui different d'une espece ä l'autre sont la presence ou absence d'elements irreguliers, le nombre de tapements de pieds par serie et les intervalles entre eux.
A comparative study of the behaviour of six taxa of male and female gerbils (Rodentia) in intra-a... more A comparative study of the behaviour of six taxa of male and female gerbils (Rodentia) in intra-and interspecific encounters. Ethology 91,2545.
Public perception of "declining standards" in school-leaving examinations often accompanies incre... more Public perception of "declining standards" in school-leaving examinations often accompanies increases in pass rates in schoolleaving examinations. "Declining standards" to the public means easier examination papers. The present study evaluates a South African attempt to estimate the level of difficulty, as distinct from cognitive demand, to exit-level examination papers in Life Sciences. A team of four expert raters assigned a level of difficulty ranging from 1 (easy) to 4 (very difficult). Invalid items were assigned a difficulty level of 0. The reference point was "the ideal average South African learner." Discussion and practice was conducted for 12 examination papers, followed by individual analysis of four examination papers. Inter-rater agreement for the final four papers was low. Raters assigned most items to difficulty levels 1 and 2, indicating that unreliability may be caused by the instrument having too many levels. Raters' predictions of levels of difficulty supported the actual mark distribution for private school candidates, but not for public school candidates. The "ideal average South African learner" is an unsuitable reference point in the unequal educational landscape of the public school system. We recommend that the instrument be modified by reducing the number of levels of difficulty and removing the hypothetical reference point.
South African journal of higher education, Feb 1, 2016
This article illustrates how decision tree analysis, using quantitative data normally associated ... more This article illustrates how decision tree analysis, using quantitative data normally associated with deductive methodologies, can be employed to inductively generate substantive grounded theory (GT). Within the context of academic disadvantage and development, a practical demonstration is provided of how theoretical explanations for student performance may be generated. Specifically, the chemistry, physics and biology modules of a science foundation programme are examined using classification and regression tree (CART) analysis towards an understanding of the factors that best facilitate a pass in each of these modules. Together with research published elsewhere on performance in the mathematics module, and the foundation programme as a whole, the findings allowed a number of 'conceptualisations' to emerge that may become the focus for GT generation. Such a substantive theory can contribute towards an understanding, on a broader scale, of what is needed to enhance student persistence, and improve retention and throughput rates in Science, Technology, Engineering and Mathematics (STEM) in South African higher education.
Effective teaching in science requires insight into students’ personal understanding of natural p... more Effective teaching in science requires insight into students’ personal understanding of natural phenomena (Bennett, 2003). Students come to school with numerous personal experiences and beliefs as well as personal knowledge about how the world works. Such personal knowledge may be regarded as their own scientific ideas (Colburn, 2000). Children’s own ideas tend to persist after formal instruction because they are based on their everyday experience of these natural phenomena.
Etude des mecanismes comportementaux par lesquels les partenaires potentiels sont reconnus. La lo... more Etude des mecanismes comportementaux par lesquels les partenaires potentiels sont reconnus. La longueur et la classe du cycle œstrien sont determines et l'œstrus est induit artificiellement par injection d'hormones
Thirty-one staged interactions between male-male, female-female and male-female pairs of captive ... more Thirty-one staged interactions between male-male, female-female and male-female pairs of captive Dasyurus hallucatus were video recorded. No contact-promoting behaviour such as huddling or allogrooming was observed. Animals performed solitary exploration of the test arena, were inactive, performed olfactory investigation and scent-marking, watched or reacted to the opponent with agonistic behaviour. Two threat postures were identified: a "straight threat" was positively correlated with submissive behaviour and indicated a defensive motivation. A "shuffle threat" was associated with aggressive behaviour and indicated an offensive motivation. Hissing vocalizations were associated with threatening behaviour, particularly straight threatening. Sniffing vocalizations were associated with agonistic behaviour. Squawks were always associated with attacking and fighting. Behaviour differed significantly among encounter types. Males performed more agonistic behaviour and less exploratory behaviour than females in same-sex encounters. In male-female encounters, females displayed more submissive and less sniff/marking behaviour than males. D. hallucatus conform to observations that most dasyurid species are solitary and asocial.
The legacy of the inequities of South Africa’s apartheid past and the shortcomings of the post-ap... more The legacy of the inequities of South Africa’s apartheid past and the shortcomings of the post-apartheid schooling systems have resulted in a particular underrepresentation of Black African graduates in the fields of science, technology, engineering and mathematics. Extended curriculum programs have been an important mechanism for redress and massification in South African higher education, offering students from disadvantaged educational backgrounds an alternative route to tertiary study. Although equity of access has improved considerably, severe challenges to realizing equity of output remain. Amid increasing student diversity within higher education, a national call has been made to interrogate the performance of extended curriculum programs at a local level in search of clues as to how the country’s educational goals of effective transformation, inclusion and improved science graduate output can be achieved. One such program is reviewed to give context to an examination of alternative access student performance in a mainstream module. The evident success of foundation students in particular relative to the majority of direct entrants suggests that students who exceeded the stipulated mainstream admission criteria by a narrow margin and who experienced further challenges related to their proficiency in the medium of instruction (English) were disadvantaged by not having completed an access year. These findings are considered in light of the growing sentiment in South Africa that the full value of curriculum extension will only be realized when it is taken to scale, becomes an integral element of mainstream provision, and is thus available to the full range of students who will benefit from it.
Sounds produced by individuals of the species Tatera afra, T. leucogaster and Desmodillus auricul... more Sounds produced by individuals of the species Tatera afra, T. leucogaster and Desmodillus auricularis during male-female encounters were analysed according to form, duration, upper frequency limit and lower frequency limit. T. afra vocalized significantly less frequently than T. leucogaster or D. auricularis, and vocalizations were detected at audible and ultrasonic frequencies. Three audible sounds had fundamental frequencies of 1.6-5.3 kHz and second to sixth harmonics were recorded. Ultrasonic whistles covered the frequency range 34 kHz to 20 kHz, and consisted of upsweeps, downsweeps, or unmodulated tones. 'Short 1 whistles had a duration < 225 msec, while 'long 1 whistles had a duration > 225 msec. T. leucogaster vocalized audibly at 5.5 kHz descending to 4.8 kHz, with third, fourth and fifth harmonics present. Long whistles of roughly the same form as those of T. afra were emitted, but these were significantly longer in duration and higher in frequency than those of T. afra. " Low peeps " at frequencies of 45-37 kHz and " high peeps " at frequencies of 66-60 kHz were also identified. D. auricularis vocalized most frequently of the three species studied, with a highly modulated trill between 54 kHz and 44 kHz. Calls in this species were often emitted as a series of trills of variable duration. Little evidence of divergence in acoustic signalling system was identified when results for T. brantsii were compared with those of its closely-related allopatric congener T. afra. Sympatric species D. auricularis, T. leucogaster and T. brantsii differed significantly in acoustic signals. Resume.-Les signaux acoustiques de 3 especes, Tatera afra, T. leucogaster et Desmodillus auricularis, ont ete etudies lors de rencontres mäle-femelle et decrits pour leur forme, leur duree et leurs limites inferieure et superieure de frequences. T. afra vocalise moins froquemment que T. leucogaster et D. auricularis. Trois cris audibles ont leurs frequences fondamentales comprises entre 1,6 et 5,3 kHz et presentent des harmoniques (H2 ä H6). Des sifflements ultrasonores compris entre 20 et 34 kHz presentent des
Special thanks go to my husband, Rob Dempster, for his assistance with the programming and for hi... more Special thanks go to my husband, Rob Dempster, for his assistance with the programming and for his encouragement and patience during this study. My children, Cheryl , Bruce, and Heather have assisted with trapping and feeding animals and have cooperated wonderfully with the difficulties of having a mother who is also a student.
Taxonomies of cognitive demand are frequently used to ensure that assessment tasks include questi... more Taxonomies of cognitive demand are frequently used to ensure that assessment tasks include questions ranging from low to high cognitive demand. This paper investigates inter-rater agreement among four evaluators on the cognitive demand of the South African National Senior Certificate Life Sciences examinations after training, practice and revision. The taxonomy used was based on the cognitive dimension of the Revised Bloom's Taxonomy, with analysis, evaluation and synthesis combined into one category. Descriptors from the Revised Bloom's taxonomy were slightly modified to suit Life Sciences. Inter-rater agreement was poor to fair, but pairwise percent agreement did not reach acceptable levels. Evaluators found it difficult to assign cognitive demand to examination items, and constantly referred to the descriptors. We question the usefulness of a taxonomy of cognitive demand when individuals differ in their interpretations of the levels of cognitive demand. The results indicate that standards of Life Sciences examination papers cannot reliably be assessed by evaluating cognitive demand using Bloom's Taxonomy.
Southern African gerbils comprise 3 genera, each genus represented by morphologically-lad ecologi... more Southern African gerbils comprise 3 genera, each genus represented by morphologically-lad ecologically-similar species. All species are monomorphic, with social systems varying from a s d (Desmodiffus anncuhnj) to colonial (Tatera species). This study compares the behaviour patterns of an allopatric species, T. &a, 2 symp-! species, T. feucogaster and T. brantsii, and a species of a different genus, D. auricularis which a sympatric with T. leucoguster and T. bruntsii. Interactions between males and females of the same species were staged and quantified in u r~~ of the frequencies of each of 23 behavioural acts. D. uuncularis performed 2 acts, namely 'sidle' md 'fight" which have not been identified in Gerbilltrrns or Tutera interactions. Sequences of behawere similar in all species, and involved females moving away from males, which followed, sniffedlb anogenital region and attempted to mount the females. Females responded by presenting, if recepat% or agonistic behaviour such as aggressive or upright postures. Exploration of the terrarium a c c o d for a large proportion of the behaviour during the 20 min encounter, and watching the opponent a d occurred frequently. Discriminant function analysis successfully separated all 4 species on the basis of beha\io@ frequencies. Individuals were assigned to the correct species with an accuracy of 80 %, indicating rbf each species exhibits species-specific patterns of behaviour. D. auricnlanj displayed more ago* and sexual behaviour and less huddling behaviour than any of the Tatera species. T h e symparric species-pair, T. feucogaster and T. bruntsii, exhibited more significant differ@ in behaviour than either of the allopatric species-pairs, T. ufru and T. brantsii, and T. ./.I T. feucogaster. Divergence in behaviour patterns has occurred in allopatric species, but divergead ' more marked in species which are sympatric. It is not known whether divergence b e m d T. leucogaster and T. bruntsii occurred during a period of allopatry, or whether divergence b, occurred due to selection against hybrids in sympatry.
Page 1. Crossing Over The Basics of Evolution Workbook for Teachers Edith Dempster Funded by The ... more Page 1. Crossing Over The Basics of Evolution Workbook for Teachers Edith Dempster Funded by The Royal Netherlands Embassy Page 2. Compiled by the Social Cohesion and Identity Research Programme of the Human ...
Vocalisations of Northern Quolls, Dasyurus hallucatus, were recorded during staged interactions b... more Vocalisations of Northern Quolls, Dasyurus hallucatus, were recorded during staged interactions between pairs of the same sex and different sexes. Four types of vocalisations were identified: 'hisses', 'sniffs', 'squawks' and 'twitters'. No pure ultrasonic calls were identified, although frequencies of twitters and sniffs extended into the ultrasonic range. All vocalisations were broadband, noisy sounds, with little evidence of harmonic structure or frequency modulation. Vocalisations of D. hallucatus are compared with data for other dasyurid species, and the correlation between frequencies of vocalisations and maximum sensitivity of the brain auditory pathway is discussed.
Concerns have been raised in the scientific community that many teachers do not accept evolution ... more Concerns have been raised in the scientific community that many teachers do not accept evolution as a scientific, testable phenomenon, and this is evident in their teaching. The non-acceptance of evolution theory is often heavily influenced by religious groups that endeavour to eliminate evolution from the curriculum. In South Africa, the inclusion of evolution in the curriculum is a recent event. This study focused on teachers’ views of evolution in relation to their religious affiliations. A questionnaire was developed and was validated by the Biohead–Citizen Project, and was then administered to more than 300 South African teachers and student teachers. Equal numbers of pre-service and in-service teachers were sampled. The groups included equal numbers of biology, English, and generalist teachers at primary school level. The results showed differences between teachers from different religions with regard to their views of evolution. Among teachers who identified as agnostic or at...
African Journal of Research in Mathematics, Science and Technology Education, Apr 2, 2015
Quantitative methods of data analysis usually involve inferential statistics, and are not well kn... more Quantitative methods of data analysis usually involve inferential statistics, and are not well known for their ability to reflect the intricacies of a diverse student population. The South African tertiary education sector is characterised by extreme inequality and diversity. Foundation programmes address issues of inequality of access by providing an opportunity for disadvantaged students with academic potential to enter mainstream degree programmes. Seeking to understand which factors are most influential in enhancing student selection and their performance in a foundation mathematics module, Classification and Regression Tree (CART) analysis is presented as a non-parametric alternative to traditional quantitative research methods. CART, a data-mining technique, is illustrated with reference to two cohorts of students enrolled in the foundation module. The two cohorts had experienced different secondary school curricula. The regression tree to examine students' final mathematics marks illustrated that the primary performance indicators for both cohorts related to the alternative selection criteria, whereas school-level performance was of little consequence. The classification tree showed that passing the module depended on socio-economic, and not academic, indicators, irrespective of school history. The hierarchy of context-dependent influences revealed in the trees illustrated that no single variable can be the basis for a framework for practical and policy responsiveness in a context of such student diversity.
This study investigated pre-and postmating isolation in two karyotypically identical gerbil speci... more This study investigated pre-and postmating isolation in two karyotypically identical gerbil species, Tatera afra and T. brantsii. The species are allopatric and morphologically distinguishable, with no natural hybrids having been reported. Evidence of premating discrimination between conspecifics and heterospecifics was inconclusive. A trent towards more nasal and anogenital sniffing, and less perineal dragging in conspecific than in heterospecific pairings was observed, but differences were statistically significant in only a few pairings. Hybrid litters were produced from six out of 16 heterospecific pairings. 50 % of hybrids died before 5 months of age, and male hybrids were more vulnerable than females. No hybrid pairings have resulted in offspring, but 1 out of 3 backcross pairings between female hybrids and pure-bred males have resulted in a normal litter. Evidence suggests that despite the lack of chromosomal divergence often associated with specialion events in rodents, postmating isolation through hybrid disadvantage and possibly male sterility is operating. Pre-mating isolating mechanisms seem to be poorly developed. Resume.-Chez deux especes de Gerbillides dont le caryotype est identique, Tatera afra et T. brantsii, on a etudie 1'isolement reproductif pre-et postcopulatoire. Ces especes sont allopatriques et morphologiquement distinctes. On n'en connait pas d'hybrides naturels. On n'a pas pu metlre en evidence de preuve concluante d'une discrimination precopulatoire entre individus conspecifiques ou heterospecifiques. Toutefois on a pu observer des tendances plus marquees au flairement nasal et anogenital, et moins marquees au frottement perineal chez des couples conspecifiques que chcz les heterospocifiques, mais les differences n'ont ete statistiquement significatives quc dans quelques couples. Six sur 16 couples heterospecifiques ont produit des portees hybrides. Mais 50 % des hybrides sont morts avant Tage de 5 mois, les hybrides males elant plus vulndrables que les femelies. Aucun couple d'hybrides n'a eu de jeunes, mais Tun des 3 couples de croisements en retour entre femelles hybrides et males de souche pure a produit une portee normale. En depit de absence de divergence chromosomique, sou vent associee ä la speciation chez les rongeurs, Fisolement reproductif postcopulatoire agit en desavantageant l'hybride et probablement en favorisant la sterilite male. Les mecanismes d'isolement precopulatoire semblent tres peu developpes.
Elephant-shrews produce acoustic signals by tapping their hindfcet. Footdrumming is elicited in l... more Elephant-shrews produce acoustic signals by tapping their hindfcet. Footdrumming is elicited in laboratory populations by disturbance and during agonistic encounters. Species-specific patterns of footdrumming have been described for several rodent species. The purpose of the present study was to find out whether footdrumming patterns are species-specific in the five South African Elephantulus species, and if so, whether the evolutionary patterns of development could be determined. Species included in this study were £. edwardii. E. rupestris, E. brachyrhynchus, E. myurus and E. intufi. Footdrummings were recorded and analysed using a sonograph. Footdrums are emitted in a series consisting of one or more bouts, each footdrumming bout being made up of one or more footdrums, usually between 25-50 msec, apart. Each elephant-shrew species has a distinctive pattern of footdrumming. Parameters which differ among species include absence or presence of irregular elements, number of footdrums per bout, number of footdrumming bouts per series and intervals between successive footdrums. Resume.-Les Elephantulus produisent des signaux acoustiques en tapant du pied. La podophonie cst declenchee en laboratoire lorsque les animaux sont perturbes et au cours de rencontres agonistiques. DC la podophonie propre ä chaque espece a etc decrite chez plusieurs rongeurs. Dans cette etude nous nous proposons de rechercher si la podophonie est specifique chez les cinq especes d'Elephantulus d'Afrique du Sud, et dans ce cas, si des Schemas de developpement cvolutif peuvent etre mis en evidence. Les podophones ont ete enregistres et analyses avec un sonographe. Us sont emis en serie d'une ou plusieurs sequences, chaque podophone etant constitue d'un ou plusieurs tapements de pied, espaces en general de 25 ä 50 msec. Chaque espece d 1 Elephantulus a un schema distinct de podophone. Les parametres qui different d'une espece ä l'autre sont la presence ou absence d'elements irreguliers, le nombre de tapements de pieds par serie et les intervalles entre eux.
A comparative study of the behaviour of six taxa of male and female gerbils (Rodentia) in intra-a... more A comparative study of the behaviour of six taxa of male and female gerbils (Rodentia) in intra-and interspecific encounters. Ethology 91,2545.
Public perception of "declining standards" in school-leaving examinations often accompanies incre... more Public perception of "declining standards" in school-leaving examinations often accompanies increases in pass rates in schoolleaving examinations. "Declining standards" to the public means easier examination papers. The present study evaluates a South African attempt to estimate the level of difficulty, as distinct from cognitive demand, to exit-level examination papers in Life Sciences. A team of four expert raters assigned a level of difficulty ranging from 1 (easy) to 4 (very difficult). Invalid items were assigned a difficulty level of 0. The reference point was "the ideal average South African learner." Discussion and practice was conducted for 12 examination papers, followed by individual analysis of four examination papers. Inter-rater agreement for the final four papers was low. Raters assigned most items to difficulty levels 1 and 2, indicating that unreliability may be caused by the instrument having too many levels. Raters' predictions of levels of difficulty supported the actual mark distribution for private school candidates, but not for public school candidates. The "ideal average South African learner" is an unsuitable reference point in the unequal educational landscape of the public school system. We recommend that the instrument be modified by reducing the number of levels of difficulty and removing the hypothetical reference point.
South African journal of higher education, Feb 1, 2016
This article illustrates how decision tree analysis, using quantitative data normally associated ... more This article illustrates how decision tree analysis, using quantitative data normally associated with deductive methodologies, can be employed to inductively generate substantive grounded theory (GT). Within the context of academic disadvantage and development, a practical demonstration is provided of how theoretical explanations for student performance may be generated. Specifically, the chemistry, physics and biology modules of a science foundation programme are examined using classification and regression tree (CART) analysis towards an understanding of the factors that best facilitate a pass in each of these modules. Together with research published elsewhere on performance in the mathematics module, and the foundation programme as a whole, the findings allowed a number of 'conceptualisations' to emerge that may become the focus for GT generation. Such a substantive theory can contribute towards an understanding, on a broader scale, of what is needed to enhance student persistence, and improve retention and throughput rates in Science, Technology, Engineering and Mathematics (STEM) in South African higher education.
Effective teaching in science requires insight into students’ personal understanding of natural p... more Effective teaching in science requires insight into students’ personal understanding of natural phenomena (Bennett, 2003). Students come to school with numerous personal experiences and beliefs as well as personal knowledge about how the world works. Such personal knowledge may be regarded as their own scientific ideas (Colburn, 2000). Children’s own ideas tend to persist after formal instruction because they are based on their everyday experience of these natural phenomena.
Etude des mecanismes comportementaux par lesquels les partenaires potentiels sont reconnus. La lo... more Etude des mecanismes comportementaux par lesquels les partenaires potentiels sont reconnus. La longueur et la classe du cycle œstrien sont determines et l'œstrus est induit artificiellement par injection d'hormones
Thirty-one staged interactions between male-male, female-female and male-female pairs of captive ... more Thirty-one staged interactions between male-male, female-female and male-female pairs of captive Dasyurus hallucatus were video recorded. No contact-promoting behaviour such as huddling or allogrooming was observed. Animals performed solitary exploration of the test arena, were inactive, performed olfactory investigation and scent-marking, watched or reacted to the opponent with agonistic behaviour. Two threat postures were identified: a "straight threat" was positively correlated with submissive behaviour and indicated a defensive motivation. A "shuffle threat" was associated with aggressive behaviour and indicated an offensive motivation. Hissing vocalizations were associated with threatening behaviour, particularly straight threatening. Sniffing vocalizations were associated with agonistic behaviour. Squawks were always associated with attacking and fighting. Behaviour differed significantly among encounter types. Males performed more agonistic behaviour and less exploratory behaviour than females in same-sex encounters. In male-female encounters, females displayed more submissive and less sniff/marking behaviour than males. D. hallucatus conform to observations that most dasyurid species are solitary and asocial.
The legacy of the inequities of South Africa’s apartheid past and the shortcomings of the post-ap... more The legacy of the inequities of South Africa’s apartheid past and the shortcomings of the post-apartheid schooling systems have resulted in a particular underrepresentation of Black African graduates in the fields of science, technology, engineering and mathematics. Extended curriculum programs have been an important mechanism for redress and massification in South African higher education, offering students from disadvantaged educational backgrounds an alternative route to tertiary study. Although equity of access has improved considerably, severe challenges to realizing equity of output remain. Amid increasing student diversity within higher education, a national call has been made to interrogate the performance of extended curriculum programs at a local level in search of clues as to how the country’s educational goals of effective transformation, inclusion and improved science graduate output can be achieved. One such program is reviewed to give context to an examination of alternative access student performance in a mainstream module. The evident success of foundation students in particular relative to the majority of direct entrants suggests that students who exceeded the stipulated mainstream admission criteria by a narrow margin and who experienced further challenges related to their proficiency in the medium of instruction (English) were disadvantaged by not having completed an access year. These findings are considered in light of the growing sentiment in South Africa that the full value of curriculum extension will only be realized when it is taken to scale, becomes an integral element of mainstream provision, and is thus available to the full range of students who will benefit from it.
Sounds produced by individuals of the species Tatera afra, T. leucogaster and Desmodillus auricul... more Sounds produced by individuals of the species Tatera afra, T. leucogaster and Desmodillus auricularis during male-female encounters were analysed according to form, duration, upper frequency limit and lower frequency limit. T. afra vocalized significantly less frequently than T. leucogaster or D. auricularis, and vocalizations were detected at audible and ultrasonic frequencies. Three audible sounds had fundamental frequencies of 1.6-5.3 kHz and second to sixth harmonics were recorded. Ultrasonic whistles covered the frequency range 34 kHz to 20 kHz, and consisted of upsweeps, downsweeps, or unmodulated tones. 'Short 1 whistles had a duration < 225 msec, while 'long 1 whistles had a duration > 225 msec. T. leucogaster vocalized audibly at 5.5 kHz descending to 4.8 kHz, with third, fourth and fifth harmonics present. Long whistles of roughly the same form as those of T. afra were emitted, but these were significantly longer in duration and higher in frequency than those of T. afra. " Low peeps " at frequencies of 45-37 kHz and " high peeps " at frequencies of 66-60 kHz were also identified. D. auricularis vocalized most frequently of the three species studied, with a highly modulated trill between 54 kHz and 44 kHz. Calls in this species were often emitted as a series of trills of variable duration. Little evidence of divergence in acoustic signalling system was identified when results for T. brantsii were compared with those of its closely-related allopatric congener T. afra. Sympatric species D. auricularis, T. leucogaster and T. brantsii differed significantly in acoustic signals. Resume.-Les signaux acoustiques de 3 especes, Tatera afra, T. leucogaster et Desmodillus auricularis, ont ete etudies lors de rencontres mäle-femelle et decrits pour leur forme, leur duree et leurs limites inferieure et superieure de frequences. T. afra vocalise moins froquemment que T. leucogaster et D. auricularis. Trois cris audibles ont leurs frequences fondamentales comprises entre 1,6 et 5,3 kHz et presentent des harmoniques (H2 ä H6). Des sifflements ultrasonores compris entre 20 et 34 kHz presentent des
Special thanks go to my husband, Rob Dempster, for his assistance with the programming and for hi... more Special thanks go to my husband, Rob Dempster, for his assistance with the programming and for his encouragement and patience during this study. My children, Cheryl , Bruce, and Heather have assisted with trapping and feeding animals and have cooperated wonderfully with the difficulties of having a mother who is also a student.
Taxonomies of cognitive demand are frequently used to ensure that assessment tasks include questi... more Taxonomies of cognitive demand are frequently used to ensure that assessment tasks include questions ranging from low to high cognitive demand. This paper investigates inter-rater agreement among four evaluators on the cognitive demand of the South African National Senior Certificate Life Sciences examinations after training, practice and revision. The taxonomy used was based on the cognitive dimension of the Revised Bloom's Taxonomy, with analysis, evaluation and synthesis combined into one category. Descriptors from the Revised Bloom's taxonomy were slightly modified to suit Life Sciences. Inter-rater agreement was poor to fair, but pairwise percent agreement did not reach acceptable levels. Evaluators found it difficult to assign cognitive demand to examination items, and constantly referred to the descriptors. We question the usefulness of a taxonomy of cognitive demand when individuals differ in their interpretations of the levels of cognitive demand. The results indicate that standards of Life Sciences examination papers cannot reliably be assessed by evaluating cognitive demand using Bloom's Taxonomy.
Southern African gerbils comprise 3 genera, each genus represented by morphologically-lad ecologi... more Southern African gerbils comprise 3 genera, each genus represented by morphologically-lad ecologically-similar species. All species are monomorphic, with social systems varying from a s d (Desmodiffus anncuhnj) to colonial (Tatera species). This study compares the behaviour patterns of an allopatric species, T. &a, 2 symp-! species, T. feucogaster and T. brantsii, and a species of a different genus, D. auricularis which a sympatric with T. leucoguster and T. bruntsii. Interactions between males and females of the same species were staged and quantified in u r~~ of the frequencies of each of 23 behavioural acts. D. uuncularis performed 2 acts, namely 'sidle' md 'fight" which have not been identified in Gerbilltrrns or Tutera interactions. Sequences of behawere similar in all species, and involved females moving away from males, which followed, sniffedlb anogenital region and attempted to mount the females. Females responded by presenting, if recepat% or agonistic behaviour such as aggressive or upright postures. Exploration of the terrarium a c c o d for a large proportion of the behaviour during the 20 min encounter, and watching the opponent a d occurred frequently. Discriminant function analysis successfully separated all 4 species on the basis of beha\io@ frequencies. Individuals were assigned to the correct species with an accuracy of 80 %, indicating rbf each species exhibits species-specific patterns of behaviour. D. auricnlanj displayed more ago* and sexual behaviour and less huddling behaviour than any of the Tatera species. T h e symparric species-pair, T. feucogaster and T. bruntsii, exhibited more significant differ@ in behaviour than either of the allopatric species-pairs, T. ufru and T. brantsii, and T. ./.I T. feucogaster. Divergence in behaviour patterns has occurred in allopatric species, but divergead ' more marked in species which are sympatric. It is not known whether divergence b e m d T. leucogaster and T. bruntsii occurred during a period of allopatry, or whether divergence b, occurred due to selection against hybrids in sympatry.
Page 1. Crossing Over The Basics of Evolution Workbook for Teachers Edith Dempster Funded by The ... more Page 1. Crossing Over The Basics of Evolution Workbook for Teachers Edith Dempster Funded by The Royal Netherlands Embassy Page 2. Compiled by the Social Cohesion and Identity Research Programme of the Human ...
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