3 Act Math

Act 1

1. Which circle will fill up first?
2. Write down a guess.

Act 2

3. What information would be useful to figure this out?
4. Write down some questions you have in your head right now.

Note: The animation software animates the circles using a rate of pixels/time instead of square pixels / time.

Mix Diameter
Mix Height
Big Pancakes
Small Pancakes

Act 3


5. What would happen if the blue circle was 5% larger?
6. What would happen if the yellow circle was 5% smaller?

Common Core Standards
Analyze proportional relationships and use them to solve real-world and mathematical problems.
Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.
solve problems involving ratios, rates, and percents, including multi-step problems involving percent increase and percent decrease, and financial literacy problems
solve mathematical and real-world problems involving similar shape and scale drawings


2 thoughts on “Circles

  1. I love this resource and I share it every semester with my students! Thank you for these great resources!!

    I used this task in my middle grades methods class this week and I was left with a question. If the circles are filling up with color, wouldn’t we need to determine the rate as a ratio of “square pixels/time” since we are covering an area? It appears the answers provided in act 3 are based on “pixel/time.”

    1. Hey Shelli thank you for the kind words and the comment! Good catch! I haven’t thought about this before. You’re right that it would seem that we should be calculating square pixels/time. I’m guessing the way the software I use animates the circles is only using pixel/time. I’ll add a note to the post. Thanks for bringing this up!

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