How to get kids interested in thinking? Coke and Mentos

School has started back up again and kids are forced to once more put their video games down and pull out their thinking caps.  By threats if necessary.  I teach high school science and if there is one thing I have learned it’s that kids don’t want to think.  It hurts.  So you have to trick them into thinking by getting them interested in something.  And blowing things up always makes kids interested.

Have you ever dropped a few mentos into a 2 liter bottle of diet coke?  I mean you, personally?  No.  Stop reading, go out and buy a bottle of diet coke and a pack of mentos.  Then drop 3-5 mentos into the open bottle at the same time (Rolling up a piece of paper and stacking the mentos in the paper using your finger as a stopper works best.  Just hold the stoppered end over the neck of the soda and slide your finger back when ready.  Then move out of the way…quickly!).  I recommend doing this outside.  Go do this now.  I’ll wait…

Pretty freaking cool, right?  And kids, including high school kids, love it.  It looks awesome and it sprays diet coke all over the place.  What’s not to love?  Now here comes the tricking part:

How does it work?  How come diet coke creates a geyser when you drop mentos into the bottle?  Is it the sugar of the candy?  The sugar substitute in the soda?  The  color used in the soda?  The caffeine content?  The level of carbonation? The surface area of the candy?  A combination of several factors?

Now comes the science.  How can you students design an experiment to test these things?  What variable can they change?  What variables stay the same?  What is a good sample size?  How are you going to measure the results in order to compare them?  What conclusions can they come to once they analyze their data?  And suddenly, you’ve gone through the entire scientific method!

Observation – diet coke creates a geyser when mentos are added to it.

Ask a question – What causes diet coke to create a geyser when mentos are added to it.

Gather Info – Do a little research on the internet to help guide and narrow your question.

Create a Hypothesis – A prediction based on your background info such as: If mentos are dropped in diet coke, cherry coke, and regular coke, then the diet coke will create the highest geyser.

Design an Experiment – What variables can you change to test your hypothesis?  Remember, you can only change one variable at a time.

Analyze your data – Organize your data in order to compare results

Conclusion – Did your data support or refute your hypothesis?  Remember, it’s okay if your data doesn’t support your hypothesis.  That’s what science is all about.  It just means you need to refocus your hypothesis and design another test.

This is both a fun and easy way to teach your kids about the scientific method.  It works as a two day lesson – one day to do the demo, go through some background info, and have the students design their own experiment and the second day for them to actually carry out their experiment – and the kids enjoy making their own coke geysers.  It also gets kids thinking about how science can be used in their day to day lives.  When they see things they don’t know anything about, they will think about it and hopefully wonder how that thing works.

And that’s the whole point of science. 🙂

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About DaynaJD

I'm a high school science teacher who has a love of all things science, science fiction, fantasy, Disney and nerdy.

One response to “How to get kids interested in thinking? Coke and Mentos”

  1. Amanda says :

    Awesome! I’m going to have to try this.

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