Idea 16of 22Builds onA rate compares different units
Beats per minute from 15 seconds
How do you turn 15 seconds of heartbeats into beats per minute?
Today you'll discover
- how many 15 seconds fit in a minute
- what “per” means
- how to find breaths per minute
Think first18 heartbeats in 15 seconds
How many 15-second parts make 1 minute?
Decide first, then press Next. Count the jumps that fill one minute.
Two number lines, seconds on top and heartbeats below. First 15 seconds lines up with 18 beats; then ticks at 30 and 36, 45 and 54, 60 and 72, with arcs marked plus 15 and plus 18. Then the 60-second tick is marked 1 minute, 72 heartbeats. The last step shows breaths: 4 in 10 seconds.
See the whole ideathe big idea and the key word, in one place
The big idea
Per means for each: 72 beats per minute is 72 beats for each minute.
Check your pulseCount your heartbeats for 15 seconds, then multiply by 4. That gives your beats per minute.
Easy to get wrongMultiply the beats by the number of parts, 4. Multiplying by 15 or by 60 counts far too many beats.
Key word
- per
- for each: 80 km per hour means 80 km for each hour
Ready to use it?
- Turn a count for some seconds into a count per minute.
- Say what “per” means in a rate.