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### How many folds to reach the Moon?

You probably already know that if you could fold a piece of paper 42 times the stack would reach the Moon. This always feels so unbelievable, but the math checks out! In this post, I want to share a couple handouts for students to support a discussion about exponential growth, folding paper to reach the Moon and also a few conversation starters.

Before the handouts, I like to ask students to give their best guess as to how many folds it would take a piece of paper to reach the Moon. Students will likely reply with "a million", "a hundred million", or say that we can only fold a piece of paper 7 times (world record is 12 times, but that's a world record for a reason!).

This first handout has a table that starts with a piece of paper 0.1 millimeter thick, which is about the thickness of computer paper. Students see in the table that it only takes 42 folds to reach the Moon. They see how fast the pile grows, even having started with a piece of paper so thin!

Here's the same data as a graph on the second handout. It helps better visualize just how fast exponential growth grows the pile of paper.

One question I liked asking students is how many folds it would take to reach half-way to the Moon. When the answer comes out as 41, and then that it takes just one more fold to reach the Moon, the students can't believe it. But this is the power of exponential growth. Ms. Ciciena sent this folding paper video to go along with the lesson.

Other questions that could spark classroom discussion:

"How thin will the stack of paper be once it's at the Moon?"

"Would we need a microscope to see it?"

"What if we start with a piece of paper twice as thick? Half as thick?"

The handouts in this post are in my Google Drive here:

42 Folds to the Moon handouts

Digital Math Escape Rooms

Math Word Walls

How to Graph Exponential Functions by Hand

Number Talks in High School Math