Limited knowledge of fraction representations differentiates middle school students with mathematics learning disability (dyscalculia) versus low mathematics achievement.

Fractions pose significant challenges for many children, but for some children those challenges persist into high school. Here we administered a fractions magnitude comparison test to 122 children, from Grades 4 to 8, to test whether their knowledge of fractions typically learned early in the sequence of formal math instruction (e.g., fractions equivalent to one-half, fraction pairs with common denominators) differentiates those with mathematics learning disability (MLD) versus low achievement (LA) or typical achievement (TA) in mathematics and whether long-term learning trajectories of this knowledge also differentiate these groups. We confirmed that although fourth graders with TA (n=93) were more accurate in evaluating "one-half" fractions than in evaluating "non-half" fractions (until they reached ceiling performance levels on both types of fractions), children with MLD (n=11) did not show a one-half advantage until Grade 7 and did not reach ceiling performance even by Grade 8. Both the MLD and LA groups had early difficulties with fractions, but by Grade 5 the LA group approached performance levels of the TA group and deviated from the MLD group. All groups showed a visual model advantage over Arabic number representation of fractions, but this advantage was short-lived for the TA group (because ceiling level was achieved across formats), whereas it was slightly more persistent for the LA group and persisted through Grade 8 for children with MLD. Thus, difficulties with fractions persist through Grade 8 for many students, but the nature and trajectories of those difficulties vary across children with math difficulties (MLD or LA).

Pituitary cystadenoma, enterolipidosis, and cutaneous mycosis in an Everglades ratsnake (Elaphe obsoleta rossalleni).

An 11-yr-old captive-born male Everglades ratsnake (Elaphe obsoleta rosalleni) presented with dysecdysis, hyperkeratosis, and inappetance. Two skin biopsies demonstrated a diffuse hyperkeratosis with both a bacterial and fungal epidermitis. Fusarium oxysporum was cultured from both biopsies and considered an opportunistic infection rather than a primary pathogen. Medical management was unsuccessful, and the snake was euthanized. Histologic findings included a pituitary cystadenoma arising from the pars intermedia, severe intestinal lipidosis, generalized epidermal hyperkeratosis, and lesions consistent with sepsis. It is hypothesized that endocrine derangements from the pituitary tumor may have caused the skin and intestinal lesions.

Chemotherapy and radiotherapy for treatment of cutaneous lymphoma in a ground cuscus (Phalanger gymnotis).

A 15-year-old female ground cuscus (Phalanger gymnotis) was presented with an isolated ulcerated, nonhealing lesion on the lateral thorax. Histopathology and immunohistochemistry were diagnostic for cutaneous T-cell lymphoma with incomplete excision. Oral chemotherapy with CCNU (lomustine) resulted in clinical remission that lasted 255 days, with no appreciable toxicity. Tumor recurrence was treated with radiation therapy, which resulted in 120 additional days of clinical remission. Subsequently, the tumor developed at a distant site and the cuscus was humanely euthanized. A slight decrease in appetite early in disease progression was the only adverse effect noted throughout the treatment period. Oral, minimally invasive chemotherapy, and adjunct radiation therapy were viable treatment options for this ground cuscus and should be considered for treatment of neoplasia in other nontraditional species.

Intervertebral disc extrusion and spinal decompression in a binturong (Arctictis binturong).

A 10-yr-old binturong (Arctictis binturong) developed an acute onset of hind limb paralysis. Neurological examination revealed sensorimotor paraplegia. Myelography and computed tomography demonstrated a ventrolateral extradural compression of the spinal cord centered over the L3-L4 intervertebral disc space. Spinal decompression was performed via hemilaminectomy and excision of degenerate nucleus pulposus, confirmed by histopathologic examination. The binturong regained slight motor function by day 8 postoperatively but succumbed to pancreatitis 19 days postoperatively.

Maximizing Efficiency of Enrollment for School-Based Educational Research.

In this observational study, influences on research enrollment were examined in the context of an educational research study. Recruitment materials were sent to parents of kindergartners in one of 23 classes across 7 public schools, as an invitation to enroll in a longitudinal study. For the 7 classes from 2 of the schools, the school principal prepared a cover letter as an introduction to the educational study. Inclusion of this cover letter was associated with a significantly swifter pace of recruitment and, to a lesser degree, with an increase in the number of children enrolled. However, when potential confounding variables were controlled, no significant increase in final enrollment count was associated with including the cover letter. Thus, inclusion of a cover letter from the school principal did not appear to dramatically increase the number of parents who elected to enroll their child in the educational study, and it did significantly decrease (by 6 weeks) the number of weeks required to achieve final enrollment counts.

Possible explanations for children's literal interpretations of homonyms.

This study was designed to examine factors associated with literal interpretations of homonyms. Participants were 212 second graders, ages 7;0-8;11, who listened to a story containing 16 key words. The key words were homonymous words ('pseudo-homonyms'), nonsense words, or familiar words used accurately. While listening to the story, children selected an illustration of each key word. Later, they were asked to recall the key words and to justify their picture selections. There was no association between interpretation and recall accuracy for nonsense words or familiar words used accurately; however, children who accurately recalled a homonymous key word were more likely to interpret the homonym 'literally,' relative to children who failed to recall the key word. Yet most of the children who correctly interpreted the pseudohomonyms also correctly interpreted these key words. Most children correctly recalled the story context regardless of key word type, but whereas correct recall of context predicted accurate interpretation of nonsense words and familiar words used accurately, it did not do so for homonyms. Children made equivalent numbers of literal and accurate interpretations of homonyms, even when correctly recalling context. Children's justifications for their word interpretations implicated the role of metacognitive skills, particularly in terms of selective attention, as a factor influencing homonym interpretation.

Complexities in Identifying and Defining Mathematics Learning Disability in the Primary School-Age Years.

This paper is a descriptive report of findings from a prospective longitudinal study of math disability (MD). The study was designed to address the incidence of MD during primary school, the utility of different MD definitions, and evidence of MD subtypes. The results illustrate the dynamic properties of psychometrically derived definitions of MD. Different groups of children meet criteria for MD depending on which measure(s) are used for identification. Over time, a given individual may not continue to meet MD criteria, even when using the same assessments. Thus, the findings lead to cautions regarding the single-tool/ one-time assessment for a clinical diagnosis of MD. Twenty-two of 209 participants demonstrated "persistent MD" (MD-p), or MD for more than one school grade. Reading disability was relatively more frequent in this MD-p subgroup than in the remaining participants (25 percent vs. 7 percent). Reading-related skills were correlated with math achievement, as were select visual spatial skills. There was minimal overlap between groups who met either a "poor achievement" criteria or an "IQ-achievement discrepancy," and the latter was far less stable a measure over time than the former. The results highlight the complexities of defining MD and illustrate the need for more research in this area.