3 Act: Stack Em Up

One of my fifth grade teachers emailed me yesterday and asked me to teach a lesson on volume next week.  I started thinking about what the students might be struggling with and decided this was a perfect example of a 3 Act math task that would clear up some misconceptions.

I grabbed my tub of 1″ foam cubes (we use them for quiet differentiated dice) and started stacking them inside a tub.  I couldn’t find a tub or box that had easy dimensions, so I thought it would be a great way to get students to work out volume, but also to ask questions about efficiency and accuracy that might help them name the need for the formula and connect it to task.

So here are the tasks and the link to the tasks in Nearpod:

Act 1:

What did you notice?  What are you wondering?

How many cubes will it take to fill the tub.  Give an estimate that is too low and one that is too high.

Act 2:

What information do you need to find a solution?

Cubes = 1 cubic inch

Without labels:

With labels:


How many cubes will it take to fill the tub?

Act 3:

Were you right?

Who is willing to defend a solution?

Who is willing to disprove an incorrect solution? (We chose this question because after watching How Mistakes Make You Smarter, we’ve been focusing on being intentional about calling attention to incorrect answers and allowing students to analyze their own and their peers mistakes.  We talked to students about this and how they are helping others become problem solvers by sharing their wrong answers)

What’s the math?


Is this an accurate representation of volume?  Why or why not?

What could we use as a more efficient method to solve for volume that would also be more accurate?

What is the volume of the tub? (8 1/2″ x 11″)


5 thoughts on “3 Act: Stack Em Up

  1. Pingback: Making Surface Area Visual | mscastillosmath

  2. I tried to open this in nearpad and it says I need to enter a code. Do you know what that code is or how I get it? Thank you.

    Also, I just found your website linked from Graham Elliott and I’m loving it!


    Liked by 1 person

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