Developing high-fidelity mental models of programming concepts using manipulatives and interactive metaphors
- Authors: Funcke, Matthew
- Date: 2015
- Subjects: Computer programming -- Study and teaching (Higher) , Computer programmers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4707 , http://hdl.handle.net/10962/d1017929
- Description: It is well established that both learning and teaching programming are difficult tasks. Difficulties often occur due to weak mental models and common misconceptions. This study proposes a method of teaching programming that both encourages high-fidelity mental models and attempts to minimise misconceptions in novice programmers, through the use of metaphors and manipulatives. The elements in ActionWorld with which the students interact are realizations of metaphors. By simple example, a variable has a metaphorical representation as a labelled box that can hold a value. The dissertation develops a set of metaphors which have several core requirements: metaphors should avoid causing misconceptions, they need to be high-fidelity so as to avoid failing when used with a new concept, students must be able to relate to them, and finally, they should be usable across multiple educational media. The learning style that ActionWorld supports is one which requires active participation from the student - the system acts as a foundation upon which students are encouraged to build their mental models. This teaching style is achieved by placing the student in the role of code interpreter, the code they need to interpret will not advance until they have demonstrated its meaning via use of the aforementioned metaphors. ActionWorld was developed using an iterative developmental process that consistently improved upon various aspects of the project through a continual evaluation-enhancement cycle. The primary outputs of this project include a unified set of high-fidelity metaphors, a virtual-machine API for use in similar future projects, and two metaphor-testing games. All of the aforementioned deliverables were tested using multiple quality-evaluation criteria, the results of which were consistently positive. ActionWorld and its constituent components contribute to the wide assortment of methods one might use to teach novice programmers.
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- Date Issued: 2015
An investigation into the captive spawning, egg characteristics and egg quality of the mud crab (Scylla serrata) in South Africa
- Authors: Churchill, Giles John
- Date: 2004
- Subjects: Scylla serrata , Crabs -- South Africa , Scylla serrata -- South Africa , Crabs -- Eggs -- Incubation , Crabs -- Spawning
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5376 , http://hdl.handle.net/10962/d1015963
- Description: The source of a reliable supply of seed is one of the most important factors determining the success of aquaculture. At present mud crab culture is reliant on wild caught juveniles, which limits the expansion of mud crab farming globally. This, coupled with the paucity of knowledge of the spawning and egg characteristics of mud crabs, prompted the investigation into the captive spawning, incubation and egg quality of Scylla serrata in South Africa. A total of 112 mature females were caught from three estuaries in northern KwaZulu Natal and acclimated to captive conditions. Mature females were present in the estuaries throughout the year and ranged from 90 to 200 mm carapace width. Except for 40 crabs all the females spawned in captivity. On average spawning took place 38 ± 23 days after capture but was not dependent on crab size. Fecundity was significantly correlated to crab size (p = 0.026), with larger females producing more eggs. The average fecundity per batch was 5.79 ± 2.07 million eggs. Hatch success rate for all egg batches was high averaging 84 ± 6 %. Egg dropping occurred in all egg batches during incubation. On average 6.5 % of the egg mass was dropped during incubation. At the average temperature of 27⁰C eggs in the incubation system hatched within 292 ± 12 hours after extrusion. In-vitro incubation of eggs proved to be an ineffective means of incubating Scylla serrata eggs with a hatch success rate of only 25 ± 5 %. Egg quality was assessed both directly, using variables such as hatch success rate and hatch synchronicity and retrospectively by using stress tests and comparing survival of larvae from different coloured egg batches. Lipid class composition and fatty acid methyl ester content for 28 batches of eggs and 16 batches of larvae were analyzed. The biochemical composition of the egg was correlated to survival of larvae in the stress tests to ascertain if the lipid content of the eggs determines their quality. Stress tests were used to retrospectively assess egg quality. Four stressors were administered to newly hatched larvae and the LD50 values recorded. An average LD50 of 64 hours was recorded for the starvation tests, 40% for the salinity tests, 37 ppm for the formalin tests and 39.7 mg/l NH3 for the ammonia stress tests was recorded. Egg colour ranged from pale yellow to orange-red. Egg colour was not influenced by female size or the time the females spent in captivity prior to spawning. Egg colour can therefore not be used as an indicator of quality. The lipid profiles of newly extruded eggs had no effect on hatch synchronicity or hatch success rate. However, the stress tests identified female size (p ≤ 0.02), DHA content of the egg (p ≤ 0.02), Σ omega-3 fatty acids of eggs (p ≤ 0.02) and EPA content of eggs (p ≤ 0.007) as possible determinants of egg quality. Larger crabs tended to produce poorer quality eggs. Egg quality also decreased as the amount of DHA, EPA and the Σ omega-3 fatty acids decreased in the eggs. To summarize, the results of this study indicated that the following parameters affect egg quality - crab size, DHA, EPA and Σ omega-3 fatty acid content of eggs.
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- Date Issued: 2004