One Brick: Exponential Growth | Pensacola MESS Hall

One Brick: Exponential Growth

Do you have a lot of Lego bricks at your house?

Try this mathematical challenge based on the One Grain of Rice folktale.

In that story, a young woman asked the rajah for only one grain of rice. When he protested that one grain wasn’t enough, she suggested that each day she returned, he could give her double what he gave her the day before. She returned every day for thirty days total. How many grains of rice did she end up getting?

You can see this exponential rise in the amounts yourself.

Starting with one Lego brick, begin doubling how many bricks you put in a container or pile. Double of 1 is 2. Double of 2 is 4. Double of 4 is 8. So on, and so on.

Let older kids do the math themselves, either through addition or mulitplication. Those who know exponents can predict how many Lego bricks you’ll count for the next doubling.

If you don’t want to count all those Lego bricks, hand your kids some dried beans or even a bag of rice to envision this mathematical folktale.

Mess Around

Can you devise a formula to calculate the total amount of bricks after 30 days?

Figure out the volume of a building needed to contain all of the bricks.