Earth’s History….on a roll of toilet paper

Sometimes it seems like teenagers think the whole universe revolves around them and their whims and woes (though perhaps, scientifically, that would be a rotation and not a revolution). Every text message is a crisis, every band breakup needs an emotional processing space, and a failing test grade is the end of the world!

One of the beauties of science, in my opinion, is that it gives us all a bigger perspective on life and reminds us that, in the grand scheme of things, we are tiny insignificant blips in a massive universe (see Scale of the Universe lesson). We are also tiny, insignificant blips in the scope of history and this lesson illustrates just that, while also providing key facts about Earth’s geologic history.

Geology? For most students, Geology = Boring, so we bring in a fun and different medium for teaching this topic….Toilet Paper!

For the record…this is the correct way to put toilet paper on the roll. The sheets should go over the top!

Start by handing out the student guide and having students work in small groups to make an estimate about when they think each event on the timeline occurred. I start by giving them a reference that our best estimate right now is that Earth formed 4.6 billion years ago.

After students have made their estimate you can introduce the activity: making a timeline of Earth’s history as toilet paper. Each square of toilet paper will represent 20 million years. If you want to throw in some extra math, you can have students convert their year estimates into sheet of toilet paper estimates (i.e. student estimated that the age of the dinosaurs began 40 million years ago, so that would be 2 sheets of toilet paper).

The starting point for our timeline will be the formation of the Earth 4.6 billion years, or 230 sheets of toilet paper ago. Personally, I find it easiest to have a student take the first sheet of toilet paper, hold that as sheet #230, and then have another student count backward to the next event, Earth’s crust solidifying, which occurred 3.8 million years ago or at toilet paper square #190.

Continue onward, having students write down the actual number of years and compare with their predictions from the handout.

You can find the full list of dates and toilet paper square numbering on this teacher guide.

It is pretty amazing to think about all that toilet paper rolled out and we humans have only existed at the very final edge of the very last piece! A great starting point for student discussion.

That’s it – a simple, straightforward, and memorable activity. This is an excellent introduction to a geology or plate tectonics unit or can be used as a stand alone activity on scaling and math.

Let me know in the comments how you might use this activity and, as always, feel free to email or get in contact ( if you have questions or would like additional supplementary resources. Enjoy!

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