The Arizona STEM Acceleration Project

Dancing Raisins!

Dancing Raisins!

a.k.a. Sewer Slugs

Laura Mitchell

6/22/24

5th grade

Notes for teachers

This experiment has been around for a long time - it’s an “oldie but a goodie” - but I wanted to share it with you in case you had never heard of it. I have also added a few elements to the original experiment.

List of Materials

• tall glass beaker or container (for the initial demonstration)
• a tall clear container for each team (could be plastic recycled containers)
• Mountain Dew and/or seltzer water (approx. 6 cans)
• raisins (regular size, about 15 per team)

Standards

Students will look at how raisins “dance” in carbonated liquid. They will wonder and hypothesize about why the raisin goes up and down in the container. They will learn about density. In math, they will get an introduction to the 6th grade standard of finding the mean of a set of data.

Standards

Objective:

To pique students’ curiosity with the phenomena of a raisin (a.k.a. sewer slug) moving in carbonated beverages. Students will observe and then create a hypothesis for why the raisin goes up and down in the carbonated liquid.

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Agenda (lesson time)

You should break your class up into teams of 3 or 4 kids.

This lesson should take about an hour.

Intro/Driving Question/Opening

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There are 2 options depending on your personal style:

1. Straightforward “dance” approach: Do a demonstration in front of the class of the dancing raisins. Put some carbonated liquid in the glass container and then add a few raisins. If the raisins are old or dried out, you may need to put a little baking soda on them. You could even play some dance music as the raisins move up and down.🎵
2. Silly/teasing approach: Tell the kids that you got a sample from the City of Phoenix Water and Sewer Department and that they are having trouble with slugs (or leeches) in the sewer system. Tell them that the liquid is sewer water and that the raisins are “slugs”. Tell them we are going to help solve the issue of the slugs reproducing and clogging up the sewer system. If you really want to gross them out, you can take a drink of the liquid (to make them think you’re drinking sewer water!!). After you gross them out, be sure to tell them you were joking and that they are just raisins!!

Hands-on Activity Instructions

1. The students should be in teams of 3 - 5.
2. Give each team a clear container with some Mountain Dew (or just seltzer water is fine too), 10-15 raisins, and a stopwatch.
3. Ask the students to write down their observations about what is happening to the raisins. What do they notice and wonder?
4. Ask the students to form a hypothesis about why the raisins are going up and down.

Explanation (hopefully the kids will figure this out on their own):

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The nooks and crannies on the raisin allow the bubbles of carbon dioxide from the soda to stick to the raisin. These bubbles decrease the density (mass per unit of volume) of the raisin and cause the raisin to rise to the surface. At the surface, the bubbles pop, increasing the density of the raisin, and the raisin sinks.

Hands-on Activity Instructions (continued)

Put a variety of other objects out for teams to test to see whether they “dance” or whether they only float or sink. They could try chocolate chips, grapes, popcorn kernels, etc. They may need to put some baking soda on the objects, and some may not work at all. Ask students to analyze what characteristics of each item enables it to “dance” or not “dance”.

Math: Data Analysis- You could let the kids experiment with other liquids to see which ones make the raisins “dance” (regular water, other carbonated drink, lemonade, etc.). They should also time how long it takes the raisins to go all the way up and down and find the mean (average) of the times for each raisin.

Questions you could ask:

• What attributes of the raisin make it “dance”?
• Do you need a carbonated liquid to make this work? Why and why not?
• How long (on average) does it take a raisin to go all the way up and down?
• What forces are acting on the raisin?
• What is Archimedes’ Principle and how does it relate to this experiment?

Other activities

You can watch this video for help setting up the demonstration:

https://www.youtube.com/watch?v=0l3M46MyfYk

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You could let the kids experiment with other liquids to see which ones make the raisins “dance” (regular water, other carbonated drink, lemonade, etc.).

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Differentiation

This lesson should be accessible to all students. Some students may need an explanation of what “density” means. You could ask them why a rock sinks in water but a balloon floats.

Remediation

Extension/Enrichment

Challenge students to think of other objects that might “dance” in a carbonated liquid. They could try chocolate chips, grapes, popcorn kernels, etc.). They may need to put some baking soda on the objects, and some may not work at all. Ask students to analyze what characteristics of each item enables it to “dance” or not “dance”.