Mowing the Lawn – Three-Act Math Task

Real World Mathematics Using Proportional Reasoning, Linear Equations & Measurement

Mowing the Lawn Real World Math - Lawnmower ZoomoutIn the Mowing the Lawn task, students will have an opportunity to utilize skills related to proportional reasoning, linear equations, and measurement after watching the information Mr. Pearce collected while mowing his lawn. This activity is geared for his grade 9 applied class, however it can be modified to suit many other levels.

Math Topics Related To This Activity:

  • Proportional reasoning
  • Linear equations
  • Finding the area of composite figures.


Act 1: Introducing the Task


Some images to assist:

Mowing the Law - Real World Math - Front Yard View

Mowing the Lawn Real World Math - Lawnmower Zoomout

Problem To Be Solved:

How long will it take Mr. Pearce to mow his lawn?

Some prompts for students:

  • What could we do to find low long it will take to Mow the Lawn?
  • What information will be necessary to help us decide?

Act 2 – Providing the Details


Act 3 – Watch for the Solution


Consolidation & Discussion

I really like this problem because there really is no way for all students to come to the same answer. There are so many variables that affect the solution (how fast I’m walking, turns, objects in the way, etc.) that we can only expect students to come to reasonable answers. This is great because it helps students learn that math is about the process rather than the final answer.

Try out the problem and let me know how you like it below in the comment section!

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7 comments on “Mowing the Lawn – Three-Act Math Task

  1. Wow! Kyle, I’m loving this task. So many students say “why do we need to know this” but you’re making math a reality-based thing. I bet no one in your class ever asks that question! I’m going to think about how I can use this kind of problem with my grade 5s. You’ve got my wheels turning…

    • Kyle Pearce Kyle Pearce says:

      Thanks for the feedback!

      I think a problem like this could be adapted for many different levels as modifying the question is quite easy.

      If you create any of your own problems, I’d love to check them out. Be sure to Check out Dan Meyer’s problems as well since they are pretty open ended!

  2. amyscal says:

    I think we will be using this problem Monday. Thanks for sharing. We will also be determining the volume of fertilizer you need to buy to cover your beautiful lawn with a 2 inch depth in preparation for the winter.

  3. Helene Matte @mmehmatte says:

    We have used this problem in grade 8 as a diagnostic. Amazing question from kids! Some worked on the perimeter, area, distance travelled by the mower and of course how long will it take to do the whole yard. Increased engagement and curiosity. Differentiation at its best. Have used it to co-construct success criteria for Thinking and Knowledge. By the way we are a french school in Ottawa. Plan on using Mustard mayhem soon. Thanks for sharing.

    • Kyle Pearce Kyle Pearce says:

      Thanks for the feedback! Glad to hear that you are finding the problems useful! Really encouraging to keep thinking of new ones to share.

      Good luck and stay in touch!

  4. Andrew Busch says:

    Kyle, I just found your site yesterday. I’m loving the videos! I have a quick tech question: how are you adding the timer over the top of the video (Act 2 Lawn mower)? I’m starting to make some 3 Act videos of my own and would rather nor record a video of a stop watch and insert it.

    • Kyle Pearce Kyle Pearce says:

      Hi Andrew:
      Thanks for the feedback! Glad you’re finding the tasks useful. Make sure you check out Dan Meyer’s tasks in the 3 Act Math list because his are just awesome.

      As for the timer, I am using Final Cut ProX with a Motion template. Not super easy if you are new to Final Cut, but there are some great tutorials out there. Give me a shout if you want me to find you a good link to help!

      Good luck and let me know if you get any tasks completed so I can add them to the list!


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