How Much Paint Do We Need?

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Students will be able to apply their measurement and area strategies to figure out how much paint will be needed to cover the surface of the bat houses.

Big Idea

This lesson is a real world task that combines many skills the students have learned throughout the school year.


15 minutes

Today is the first day the students the students will see the cut wood for the bat house assembly.  I am expecting a lot of excitement around today's lesson, as well as all of the rest for this project, as now it is actually "real"!

I intend to capture this excitement with a simple question.  "What do we know about bat homes that make them safe and successful as roosts?"  We have been studying this in our reading workshop, so I am listening for the students to get to the point that the houses need to be hung in an area with enough sun, or painted black to absorb heat. 

When they remind each other of this, I will present the problem.

What do we need to figure out in order to make sure we buy enough paint?  Here, we begin discussion of area. 

Active Engagement

30 minutes

The students are sent off in their building teams with their box of bat house pieces.  They will grapple together to find the area of all sides, except the interior sides.  Next, they will figure out that they need to add all of those areas together in order to find the total space to be painted. 

This team struggles with how to find the area of the triangular piece of their board.  Their conversation was very authentic and their ideas are sound.  I step in only when they begin to get frustrated and simply reviewed a few rules of finding area. Then I facilitate their conversation so that they ultimately realize they can find the area of a "pretend" rectangle of the same length and width and divide it in half to get the area of the triangle. 

In this clip, you will hear the students review how they finally figure out the total area of this board.  Although it looks simple, these girls persevered for 15 minutes on this one problem!  Now that's math.

I include this clip to show how my students apply some of their basic skills learned this year to figure out a much more challenging problem.  This student combines breaking apart a number into friendly numbers, with mental math skills, to find the area of a large area. 

This video proves that all students can participate in projects like this.  This particular student does not speak as much as others, but look at all of his communication skills: models, labels, and area totals. 


10 minutes

This lesson is rich and rigorous.  Therefore, for closing, we simply share out some of the challenges encountered and how they were attacked.  I also leave room for student groups to compare area totals and volunteer advice if a team is stuck.