Genetics

Ms. J. recently attended a workshop with other teachers at the university where she learned equally from the instructors and the other attendees. She also reads research regularly, reviews resources, and makes judgments about their value for her teaching. Ms. J. engages in an iterative planning process, moving from a broad semester plan to daily details. The students in her high-school class have opportunities to develop mental models, work with instructional technology, use multiple materials, teach one another, and consider the personal, social, and ethical aspects of science. She has the support of the school and district and has the resources she needs. She also relies on resources in the community.

[This example highlights some elements from Teaching Standards A, B, D, and E; Professional Development Standards A, B, and C; 9-12 Content Standards A, C, F, and G; Program Standards C and D; and System Standards D and G.]

Ms. J. is eager to begin the school year, and is particularly looking forward to teaching a semester course on transmission genetics--how traits are inherited from one generation to the next. She taught the course before and read extensively about the difficulties students have with transmission genetics conceptually and as a means of developing problem-solving skills. She also has been learning about new approaches to teaching genetics. From her reading and from a workshop she attended for high-school teachers at the local university, she knows that many people have been experimenting with ways to improve genetics instruction. She also knows that several computer programs are available that simulate genetics events.

Ms. J. is convinced that many important learning goals of the school's science program can be met in this course. She wants to provide the students with opportunities to understand the basic principles of transmission genetics. She also wants them to appreciate how using a mental model is useful to understanding. She wants her students to engage in and learn the processes of inquiry as they develop their mental models. Ms. J. also wants students to understand the effect of transmission genetics on their lives and on society; here she wants them to address an issue that includes science and ethics.

Selecting an appropriate computer program is important, because simulation will be key to much of the first quarter of the course. Ms. J. has reviewed several and noted common features. Each simulation allows students to select parental phenotypes and make crosses. Offspring were produced quickly by all the programs; genotypes and phenotypes are distributed stochastically according to the inheritance pattern. With such programs, students will be able to simulate many generations of crosses in a single class period. All the programs are open-ended--no answer books are provided to check answers. All the programs allow students to begin with data and construct a model of the elements and processes of an inheritance pattern. Students will be able to use the model to predict the phenotypes and genotypes of future offspring and check predictions by 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 karyotyping and leave some photographs so students can try sorting chromosomes to get a feel for the skill required to do this. Having students perform a karyotype will give new meaning to a phrase in the text: "the chromosome images are sorted by type."

Each student will become an "expert" in one inherited human disorder, learning about the mode of inheritance, symptoms, frequency, effect on individuals and family, care, and such. Students will present their reports to the class. They will also work in pairs to solve an ethical case study associated with an inherited disorder. Drawing on several articles about teaching ethical issues to children, Ms. J. has created one of her own, and with the help of colleagues and the staff at the clinical genetics center, she has developed several case studies from which the students will develop their ethical issue papers. Part of the case study will require students to draw a pedigree. Ms. J. is gathering print matter: fliers from the March of Dimes, textbooks on clinical genetics, some novels and short stories about people with inherited disorders, and articles from popular magazines. This is an ongoing effort--she has been collecting material for some years now. She also has posters and pictures from service organizations she will put up around the room, but some wall space needs to be saved for student data charts.

Having reviewed the goals and structure of the course, Ms. J.'s next planning step is to map tasks by week. She has a good idea of how long different activities will take from her previous experience teaching this course. Planning for each week helps ensure that the live materials and the speakers are coordinated for the right time. But Ms. J. knows that it is likely that she will need to adjust scheduling. Ms. J. and the students will set routines and procedures during the first week; then students will do much of the class work in their teams.

Finally, Ms. J. begins to map out the days of the first week. On the first day of class, the students will share why they chose this course and what their hopes and expectations are. They might also describe what they already know about genetics and what questions they bring to class.