making the crosses. Ms. J. chooses one of the simulations after reviewing it carefully and considering the budget she has for supplies. Enough computers are available to permit students to work in teams of four.

Students will work in their teams to develop models of inheritance patterns during the first quarter. Ms. J. plans to obtain reprints of Mendel's original article for students to read early in the quarter. It has a nice model for an inheritance pattern, and students will examine it as they identify elements of a mental model. In addition to using the simulations, Ms. J. wants students to work with living organisms. She will need to order the proper yeast strains, fruit flies, and Fast Plants. She has commercially prepared units in genetics using each of these organisms and has adapted the units

to meet the needs of the students. Each organism has advantages and limitations when used to study transmission genetics; students will be working in teams and will share with other teams what they learn from the different organisms.

During the second quarter, students will focus on human genetics. Ms. J. intends to contact the local university to arrange for a particular speaker from the clinical genetics department. The speaker and Ms. J. have worked together before, and she knows how well the speaker presents information on classes of inherited human disorders, human pedigree analysis, new research in genetic susceptibility to common illnesses, and the many careers associated with human genetics. Someone from the state laboratory also will come and demonstrate