Investigates high school students' understanding of the physical relationship of chromosomes and genes as expressed in their conceptual models and in their ability to manipulate the models to explain solutions to dihybrid cross problems. Describes three typical models and three students' reasoning processes. Discusses four implications. (YP)

Discusses problem-solving strategies and the successful strategy used to solve stoichiometric problems in general college chemistry courses. Reports that rereading problems, recalling a related concept, and reasoning deductively/inductively are the most heavily used strategies among 13 categories. (YP)