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Ratios and Data 6-8 / Week 02 / Data Day
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Week 02 · Rates and Speed

Data Day

Data Day: Heartbeats and steps
// A ratio with two different units
⏱ about 20 min

Data Day: Heartbeats and Steps

Saturday morning the whole family sits around the Numbers Desk with a timer in the middle.

"Everyone finds a pulse," Raven says, showing two fingers on the side of her neck. "Count for 15 seconds."

Rocket is done first. "Nineteen! Times four is 76 beats per minute."

"What do you notice when you compare everyone's numbers?" Raven asks. "They are all different," Rocket says. "But all close."

Nova hovers above the timer. "Now try after a minute of marching in place. Predict first."

Rocket predicts 100. He counts 24 in 15 seconds. "Ninety-six. Close!"

  1. A rate is a ratio of two quantities with different units, like meters and seconds.
  2. A unit rate is the amount for exactly 1 of the second unit. Divide to find it: 40 ÷ 8 = 5 meters per second.
  3. Unit rates make comparisons fair, even when runners go different distances.
  4. Double number lines and ratio tables show a rate at many sizes. Multiply the unit rate to predict.
  5. Units change with ratios: 60 seconds per minute, 100 centimeters per meter.
◇ FAMILY PULSE AND STEP COUNT
Each person finds a pulse at the wrist or neck and counts beats for 15 seconds while someone times.
Multiply each count by 4 to get beats per minute. Write every rate in the Numbers Notebook, without names if you like.
Everyone marches in place for 1 minute, then counts again. Compare the resting rate and the moving rate.
Then count steps for 1 minute of walking. Predict how many steps 5 minutes would take.
For a grown-up
This week your student turned measurements into unit rates, like meters per second, and used them to compare and predict.
Ask them to explain why 40 meters in 8 seconds is slower than 30 meters in 5 seconds.
Marching in place is gentle exercise. Anyone who feels dizzy or unwell sits down and skips the second count.
Safety first
Count your pulse sitting down. Press gently; never press hard on the neck.
March in place on a clear floor in shoes or bare feet, never in socks on a smooth floor.
Stop and rest if you feel dizzy or short of breath.
DATA DAY CHECK
  • Read the question.
  • Tap your answer.
Rocket counts 19 heartbeats in 15 seconds. How many beats per minute?
After marching, Rocket counts 24 beats in 15 seconds. How many beats per minute?
Raven walks 110 steps per minute. How many steps in 5 minutes?
Resting, Rocket counts 76 beats per minute. After marching, 96 beats per minute. Which rate is higher?
StatementTrue or false?
19 × 4 = 76?
24 × 4 = 86?
A unit rate tells the amount for exactly 1 of the second unit.?
The runner with the longest distance is always the fastest.?
WHY THIS EXERCISECounting for 15 seconds and multiplying by 4 is ratio reasoning you can use any day.
Draw a double number line for your resting heartbeat, beats over seconds, from 0 to 60 seconds.
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