How long does it take to tie your shoes?
20 seconds 20 hours
Select the better estimate.
Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
Imagine being told that the bus leaves in 7. You might be thinking, 7 what? Does the bus leave in 7 minutes? 7 seconds?
The number 7 on its own does not give you much information about when the bus is leaving. That is because the units are missing.
Time is usually measured in units of seconds, minutes, or hours. It takes about 1 second to sneeze and 1 minute to get dressed in the morning. It takes about 1 hour to bake a pie in the oven.
There are 60 seconds in 1 minute. So, 1 second is much less than 1 minute.
There are 60 minutes in 1 hour. So, 1 minute is much less than 1 hour.
The better estimate for how long it takes to tie your shoes is 20 seconds.
20 hours is too slow.