• Tasks. The first task is for students to read the above materials and
understand that a gamete has half the number of chromosomes as
a body cell. The second task is for students to guess what happens
in the reduction division and how the number of chromosomes in
the daughter cells is reduced by half. The students must then construct a model to demonstrate their guess. Here are three examples
of student models that demonstrate these guesses (Figure 2).
What Happens in Meiosis I? What Happens in
• Expectations. Students will understand that meiosis uses many of
the same mechanisms as mitosis; the homologous chromosomes
are segregated to separate daughter cells by the spindle apparatus
in Meiosis I, and the sister chromatids are segregated to separate
daughter cells in Meiosis II. On the basis of this understanding,
students will modify their previous models.
• Resources. The resource provided is a display of the stages of meiosis (Figure 3) and an explanation of the chromosome behavior
in each phase.
• Tasks. The first task is for students to examine Figure 3 and listen
to the explanation of the chromosome behavior in each phase.
Then students must modify their previous models on the basis
of their understanding of the process of meiosis. Below are three
examples of students’ modified models (Figure 4).
What Is Meiosis?
• Expectations. Students will explain meiosis in their own words,
as well as how the process and outcome of meiosis differ from
those of mitosis.
• Resources. Students must rely on their learning about meiosis
earlier in this lesson as well as previous lessons about mitosis.
• Tasks. Students must first explain the definition of meiosis in
their own words, based on the learning from this lesson. They
must then compare meiosis with mitosis and seek to explain
the differences between these two types of cell division.
Phase 5: Applying Knowledge to
Scientific Research & Real Life
Through the process of evidence-based question answering
described above, students gain an understanding of the concepts
involved in the lesson. To examine and reinforce students’
understanding, teachers should create two more learning situations for
students to answer the questions “What are the applications of
these concepts in scientific research?” and “What phenomena in
real life can be explained by these concepts?” The learning situations designed for the application of concepts from the meiosis lesson are described below.
What Are the Applications of Meiosis in Scientific
• Expectations. Students will understand that the chromosome
behavior in meiosis provides the physical basis for explaining
• Resources. Students must rely on their recall of Mendel’s laws
learned in the previous lesson.
Figure 2. Students’ models of reduction division. All students could propose models, but most of the models were faulty.
Students’ preunderstanding of reduction division should be addressed in the following learning situation.