Estimation of Marbles STEM Challenge

Estimation of marbles challenge

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How to do the Estimation of Marbles STEM Challenge

The Challenge: Estimate the number of marbles placed in a glass jar and then verify by counting the marbles.


• Marbles
• Plastic jar

Procedure: Fill up the jar with marbles, to the neck and not to the brim.

Challenge criteria: Devise a method to approximate the number of marbles in the jar. Do not count the marbles. Make three estimations. Figure out the average of your estimations using the given formula:
Average = Sum of estimations / Number of estimations

Example: Suppose you make three estimations: 100, 99, and 101. As per the formula:

Average = (100+99+101)/3

               = 300/3

               = 100

Now, take out the marbles and count them. Cross-check your average with the counted value.


How could this skill help you in counting a stack of bricks, or a bunch of small objects? Is this technique easier than manual counting? Does the volume of the jar and marbles help make an accurate estimation? If yes, then how? What assumptions did you make to ease the process?

Challenge extension

Try estimating the number of gumballs present in a gumball vending machine.

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