Cool Math 4 Kids: Estimating Height.

A typical tape measure with both metric and US...

A typical tape measure with both metric and US units and two US pennies for comparison (Photo credit: Wikipedia)

One summer, my son got a job at 7/11.

He told me about something I’d never noticed before

There is a tape on the side of the door, as you go out, with feet and inches marked on it.

This is so if someone steals something from 7/11, the clerk can see how tall they are as they walk out the door, to help identify them to the police.

Banks have the same measuring tape on their doors.

But, there are other times you need to know, or be able to estimate how tall something is.

If you are driving into a parking garage, they tell you how tall your car can be to get in safely.

If you are a truck driver, you need to know how tall your truck is to make sure you can clear bridges you drive under.

Your grandchildren can learn to estimate height by practicing.


  • Four things to measure
  • Measuring tape or yardstick
  • Optional: three friends
  • Optional: bank


  • Have your grandchild pick out four things around the house to measure (I used a teddy bear sitting and standing, a piggy bank, and the front door.
  • Show them how to measure each item with a measuring tape or yardstick. If the item is taller than 3 feet, they will have to hold their finger at the end of where the yardstick measured, then slide the yardstick up until the bottom is at their finger and see how much higher the item is, then add the two numbers to get the full height.
  • Optional: estimate how tall each friend is, then measure them. The easiest way to do this is to have them stand against a door jamb, level a pencil across the top of their head and make a pencil mark on the door jamb, measure from the floor to the pencil mark, and put their name next to the pencil mark.
  • Optional: let your child sit in a chair at a bank, while you are doing business there, where they can see people leaving and estimate how tall each person is before they walk out by the measuring tape.

Thanks to for inspiring this activity. 

This article first appeared on 

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers


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