Lesson 13 of 14
Objective: SWBAT read and explain a pedigree.
As the students enter class, they will take out their journals and respond to the prompt: What is a pedigree? Is it useful? Why or why not?
This is information that we briefly reviewed in a previous lesson (Punnett Squares and Pedigrees - Flipped) and the students have a small segment of flipped notes on this topic. In order to understand this lesson, students need to have a basic understanding of NGSS MS-LS3-1, 2. The students are able to refer back to their notes, if they do not remember the information. Looking back at their notes helps the students become more familiar with their contents and their desire to answer the question correctly instead of just writing that they do not know the answer demonstrates their growing independence as learners. I circulate through the classroom while the students write, so I am able to see which students are referring back to their notes and which students remember the information without referencing the notes.
After providing time for the students to write their thoughts, I ask for volunteers to share their responses with the class. Some students have written their notes verbatim, so I push them to describe pedigrees in their own words and to explain whether or not they are useful. The concept is still rather new to the students, so I explain that we will be examining the topic in more depth during class.
After reviewing the students' ideas of pedigrees, I hand out the Pedigree-Analysis reading from cK-12. I ask the students to read the information up to the summary portion and to write Cornell notes on the information. I let students work with a partner of their choice as they read and take notes, but require that each student write their own notes. Working with a partner provides students with the opportunity to discuss what they are reading and to help one another make sense of the information, if they are having difficulty. I print out pages three and four for the students, so they may mark in the margins and underline information if they would like. Even if the students make marks on the article, I have them write Cornell notes as a way to practice note taking and synthesizing information. While the students read the selection and work on writing their notes, I circulate through the room to ask them about the information they have written; to double check that they are not simply copying down information but that they understand what they are writing.
When a majority of the students have finished writing their notes, I have volunteers highlight the key information from the text on the Smart board and we spend time reviewing the key elements of the drawn pedigree. I then pull up an online worksheet and ask the students to answer questions about the first pedigree. We begin with a review of the terms heterozygous and homozygous. I ask the students to tell me if the listed genotypes are heterozygous or homozygous. From there we review the information that albinism is recessive, and I call on volunteers to tell me the corresponding phenotypes for the listed genotypes.
We then move on to the second question. I begin by asking the students general questions about the pedigree. For instance, I ask them how many males are represented and how many females are represented. I ask them how many affected individuals are shown in the pedigree and how many children there are. I then call on volunteers to come to the board to fill in the genotypes for the individuals in the pedigree. I follow this protocol for the fourth question as well, asking students to identify the various elements of the pedigree and then filling in the possible genotypes. During this process, I emphasize the idea that if someone displays a dominant phenotype, it is not possible to tell if they are homozygous dominant or heterozygous unless/until they have offspring.
Developing an understanding of how to read and use pedigrees addresses NGSS SP2 (Developing and Using Models), SP4 (Analyzing and Interpreting data), and Crosscutting Concept Patterns (using charts to identify patterns).
Once I am confident that the students understand the various symbols of the pedigree, I explain the Pedigree Practice activity to them. For this activity, the students work individually or within their small groups to explore an online pedigree activity.
While the students are working, I take small groups to probe their understanding of the topic. To do this, I begin by asking the students to explain the interactive website they are working on. I then ask them to read and explain a pedigree. I also have the students work on a pedigree as a group at the SMARTBoard. While this video does not capture the students' discussion of filling in the pedigree, it does demonstrate the manner in which the work on the SMARTBoard is completed.
This video provides an overview of the three website activities students may choose from during this section of the lesson.
At the end of the lesson, I ask students to describe the websites they worked on and to share any new insights with the class. This provides the students with an opportunity to summarize the material they viewed during the lesson, which further allows them to incorporate it into their understanding of the topic. During this discussion I have the students identify the symbols for male and female as well as affected and unaffected and we review the connection between genotypes and phenotypes.