Multiple representations in web-based learning of chemistry concepts

A new chemistry curriculum for secondary schools is currently under construction in the Netherlands, in which chemical knowledge will be embedded in contexts that show applications of chemistry in the society. Several research groups develop such modules and a committee appointed by the Dutch Ministry of Education advises about the chemical content and concepts.\ud A central issue in chemistry education is the relation between the real, molecular and symbolic world. Skilled chemists switch easily between these worlds, but beginning students do not. They could get better results and will be more able to solve problems if they would make better connections between the three chemical worlds. The University of Twente has developed a series of lessons about the particle model. Included in this instruction material are animations of chemical processes at the molecular level. In the lessons students are supported and stimulated to make connections between the three chemical worlds. Students are shown the importance of new chemical knowledge in society. The mental images and the knowledge schemata of the students are investigated in this research. The students were interviewed before they received instruction, and after they received about half of the instruction. At the end of the instruction they were asked to make a concept map.\ud It appeared that the links between the real, molecular and symbolic world are not strengthened after the instruction. The students make more links between the real and symbolic world, but hardly connect these world to the molecular world or vice versa. There is still a gap between the students’ mental models and scientifically accepted models as represented in animations and illustrations in the instruction. Most students liked the animations in the instruction and mentioned them as strong point. It is therefore surprising that some students could not remember the animations when they were interviewed, whilst others their representations were about the same as the animations. Clearly, the effectiveness of the animations must be enhanced and more research is needed for this

A probabilistic analysis of the Dutch lotto

The size of the jackpot of the American powerball lottery that fell in August 2001 has generated a lot of interest in the probability of winning a lottery, both in the United States and elsewhere. Many people dream of becoming rich in a single moment. We calculate the probabilities of winning prizes, and the expected pay-off of the Dutch Lotto. We also address an important issue: are the numbers and color drawn truly random? We analyze draws of the Lotto from 1974 onwards. It is impractical to test whether each possible draw occurs according to its expected frequency. It is possible, though, to test different implications of the hypothesis that the numbers and colors are drawn randomly. We find that there is no evidence against the hypothesis that the numbered balls are drawn randomly, but the hypothesis that the colored ball is drawn randomly is rejected decisively.

History of the Grand Village of the Kickapoo Park

A narrative with supporting documents of the 6YKP and annual powwow

The main problems of food allergic consumers concerning food labeling: an ethnographic study

It has been estimated that 58% of children and 12% of the adults in developed countries are affected by food allergy, with symptoms ranging from discomfort to fatality. At present, avoidance of problematic foods is the only effective treatment strategy. As of November 25 th , 2005 food manufacturers in the EU are obliged to list 12 potentially allergic ingredients in food. Although the label is still not always fully understood by the consumer, or they get confused by precautionary labelling practices. This paper aims to gain insights into the information preferences of food allergic consumers regarding existing food labelling and additional information delivery systems. The results of this study will facilitate the development of best practices in information provision regarding food safety in the area of food allergy. In particular the research will elicit preferences for new ICT approaches to information delivery which can be focused on the individual needs of consumers. We argue that improved information supply will contribute to the quality of life of food allergic people.Food allergy, consumers, food labelling, information needs, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

The effects of food habits and socioeconomic status on overweight. Differences between the native Dutch and immigrants in the Netherlands

Overweight is a worldwide growing epidemic. The Netherlands is among the countries with the highest prevalence for overweight, together with the USA, UK, and Germany. This paper investigates differences in overweight between native Dutch and three immigrant groups in the Netherlands, and the effects of food habits and socioeconomic status on overweight. The results show that all immigrant groups have a higher prevalence for overweight than the Dutch, apart from Moroccans. Males are overweight more frequently than females. Takeaway food, eating out, and fresh vegetables decrease BMI, while convenience food, ready-to-eat meals, and delivery food (in some cases) increase BMI. In all groups, BMI increases with age. For Surinamese/Antilleans and Turks BMI increases with children living at home, whereas for native Dutch BMI decreases with children living at home. The national health expenditures due to overweight is 200 million to 4 billion Euro per year, which is 1 to 5 percent of the national health expenditures. The government and health insurance companies should try to prevent overweight and encourage healthy behavior.overweight, ethnicity, food habits, Food Consumption/Nutrition/Food Safety, C20, D12, I12,

The demand for health: differences between the native Dutch and immigrants in the Netherlands

This paper estimates the demand for health by using a health capital model for different population groups (native Dutch, Surinamese/Antillean, Moroccan, and Turkish) in the Netherlands. Also the effect of overweight on health utility is investigated. We found a decrease in the demand for health for age, overweight, and smoking, we found an increase in the demand for health for level of education and marital status. The analyses show a strong effect of gender. Being female in all groups is negatively related to health utility. Turkish and Moroccan ethnicity is negatively related to health status.demand for health, health production, ethnicity, overweight, food habits, Health Economics and Policy, C24, C25, I10, I12,