Cat Island (Day 2 of 2): Cats can’t add but they do multiply!

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SWBAT investigate an exponentially increasing sequence and make sensible estimates and assumptions based on this sequence.

Big Idea

Looking at the life cycle of cats, students use exponential models to see how quickly populations can grow in the real world.

Revisit Cat Island

2 minutes

Refresh students' memory about Cat Island and the problem they explored in the last class period by reprsenting pg. 2-9 of the flipchart (it’s just a repeat of the story from yesterday).

This lesson follows the MARS Mathematical assessment Project Modeling: Having Kittens lesson that can be found here. However, I am cutting a few pieces and speeding things up a bit so that we can wrap it up in today’s 50 minute class period (see below for details on that!).

Group Solving/Make Poster

20 minutes

Pass back students’ individual papers from Day 1 with comments on them. See page 4 of the PDF Modeling: Having Kittens lessons from the Mathematics Assessment Project for some great starting points for questions to prompt students to think about their current misunderstandings or pieces of the problem they are missing. (If you don’t have time to leave individual feedback for students I recommend looking over the papers and getting a general idea of which prompting questions would best suit your class.) In my resources, have left pg.10 of the flipchart blank so that I can add common issue questions to discuss with the whole class after reviewing their work on Day 1.

Once papers are returned to students, group students into new teams. I am going to break apart the teams students typically work with on this problem. My goal is to enable new approaches to the problem for each group. I hope richer mathematical conversations will result from mixing up the teams at this point. I may even number student’s papers as I review them and have all student with the same number group up. If I do this, I will consider different approaches to the problem as well as who will work well together.  If the teams work well together, I may make these teams their new quarter 2 teams.

Teams will work together to produce a final answer, showing their work to explain their strategy. Students will need to be able to explain their solution and should make these visuals to help explain it. I am not sure exactly yet what form I want these visuals to take. Posters? Butcher paper? Just notebook paper? Maybe large whiteboards? I am leaning more toward whiteboards (with a huge emphasis on not erasing until the end up class!) since I am not planning on collecting it.

Stay and Stray

8 minutes

Once students have had some time to formalize and agree on a solution in their teams, I am going to ask the teams to complete a Stay and Stray. One student will stay with their poster and be the expert. While the other two team members go visit different posters. The idea here is that students will check in with other teams and maybe find some ways they can improve their solutions. I am going to allow students about 2 minutes per rotation. I only plan on doing two rotations. So each ‘straying’ student will only visit two other posters, but collectively each team will gather information from 4 different posters. Then that should give students about 3 minutes to report back to their teams and discuss their findings.

Improving Solutions

20 minutes

To help get students refocus after the stay and stray I present the prompting questions I prepared on page 11 of the flipchart and lead a whole class discussion about the student work on pages 12-14. The goal of this part of the lesson is to address the misconceptions that were identified in students' individual solutions. I know there are many great conversations that could occur in analyzing the work and we could probably use a whole class period doing this, but I plan to take about 5 minutes discussing some of the constraints of and assumptions in students’ work.  After this brief discussion, the remaining class time will be given to students to improve their solutions and write their final conclusions.

For me, the primary goal of the Cat Island Investigation was for students to see what it means for a population to increase exponentially. I will be refering back to this problem throughout the Exponential Functions unit as a real life example of how quickly growth can occur when the underlying process is exponential. So I will not view the lesson as unsuccessful if all students do not come to a correct mathematical conclusion. The focus was more on developing their ability to understand the situation and to construct a model that enables further exploration.