A silhouette of a child skipping with a jump rope.Problem Solving Prompts

Learning Goals:

  • Solve problems involving the addition and multiplication of multi-digit whole numbers
  • Develop an understanding of simple multiplicative relationships involving rates
  • Communicate mathematical thinking orally and visually

The Challenge:

Manjot measures his heartbeats while sitting down and counts 21 beats in 15 seconds.
After skipping rope on the sidewalk, he measures again and counts 30 beats in 15 seconds.

How many heartbeats would Manjot have in one minute while resting?
How many heartbeats would he have in one minute after skipping?
(This is the standard way to measure heartbeats – called a “heart rate.” They are usually recorded in beats per minute, or bpm for short.)

If Manjot’s heart rate continued to be 30 beats in 15 seconds and he skipped for a full ten minutes, how many times would his heart beat in total?

Questions and Prompts to Support your Child:

  • What have you tried? If that didn’t work to get you to the total of a minute’s worth of heart beats, what could we try instead?
  • If you’re not sure how to get started, remember that there are 60 seconds in one minute!

Extensions & Adaptations:

  • If struggling with calculations, have a calculator handy!
  • Try measuring your own heart rate! Instead of counting for an entire minute, think of a shorter period of time that would be helpful in calculating your beats per minute (bpm)
  • Do some comparing! Measure your heart rate when you are resting and again while exercising. How do the rates compare?
  • Do all types of exercising affect your heart rate the same way?
    For an even bigger challenge, try tracking the time you spend exercising across an entire day, then use this information, along with your resting and elevated heart rates, to figure out approximately how many times your heart beats in a day. About how many of those heartbeats come from your resting heart rate? About how many come from an elevated heart rate due to exercise?

Source: University of Waterloo – CEMC Problem of the Week Database