We are studying Montana, and so, of course, that means we need to learn about Yellowstone national park, Old Faithful, and how geysers erupt. Which means mean needed to buy some mentos. Stick around to find out how geysers erupt in this great science lesson AND geography lesson.
(there are affiliate links in here)
Supplies for our how geysers erupt lesson
Montana printable (in the subscriber library, join my newsletter and get access to hundreds of printables), sodas (2 liters bottles are impressive, but I split our bottle into several, this was a bad decision), Mentos, and if you want Mentos dispenser (handy to get the amazing reaction, and the one I linked to also has the Mentos, but it’s always fun to have more on hand to keep trying again)
A bit of science to explain how geysers erupt
Before teaching this lesson, I didn’t know geysers were mainly in four locations, and over half of the world’s geysers are in Yellowstone National Park.
That is fascinating to me.
Geysers erupt because of a pressure and heat underground. They’re like a rebalancing of the pressure underground.
That’s why we can’t really predict when most of them erupt. The geyser mentioned in the video only erupts like every 50 years.
That’s what makes Old Faithful over in Yellowstone so interesting. It erupts ALL THE TIME. I remember traveling to Yellowstone on a family vacation and being amazed to see it erupt.
With all of that in mind, when we learned about Yellowstone, I knew it was finally time to try the Diet Coke and Mentos science experiment as a great demonstration of a geyser.
Demonstrating how geysers erupt
Full disclosure, when we attempted to show how geysers erupt, ours didn’t work. I should say, it did erupt, but we didn’t get the big explosion you expect to see. We did a lot of problem-solving to figure out why.
This is what is supposed to happen.
View this post on Instagram
Creating our homemade #oldfaithful with the classic #mentosdietcoke experiment
This is what happened with ours.
We talked over reasons our experiment might not have worked, and these are the reasons we came up with:
- Pouring the Diet Coke into the smaller bottles possibly released too much carbon dioxide.
- We did not put all of the Mentos in all at once, but they got added in slowly bit by bit.
- The wider mouth of the Gatorade bottles probably decreased the pressure a little bit.
After the failure with Diet Coke, the kids had to find out if this would work with other sodas. At this point our experiment had changed from how geysers work to “what sodas cause reactions with Mentos?”
You know what we discovered?
They all worked. It’s just a difference in how much of a mess it is and how sticky it is afterward. That is why we were outside, we finished up and hosed down the driveway.
Then for some strange reason they all decided to try drinking the sodas they’d put the Mentos in. That sounding like it would taste awful.
Afterward we headed in and wrote what we learned, and how geysers work down.
More Geography related Science Ideas
I know I have more lessons, but these were the three I came up with quickly.
- Digging up Pompeii
- Mount Saint Helen
- Dinosaur Dig
- Dig up the Hunley (I couldn’t find a picture for this one, sadness)
I would think it did not work for the first reason – that you let most of CO2 out while pouring soda from one bottle to another. But this one is always such fun regardless of the age 🙂
Sodas with mentos does sound horrible.
Geysers are fascinating.