Three Layer Float

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Biology In Elementary Schools is a Saint Michael's College student project from a course that ran between 2007 and 2010 and fully described in this book chapter. The student-created resources have been preserved here for posterity. Link under 'toolbox' for printer-friendly versions of the exercises. Click on handouts to print full resolution versions. Please see Wikieducator's disclaimer, our safety statement, and the Creative Commons licensing in English and in legalese.

Student worthiness

We have completed the experiment successfully. We are able to place each section of the liquids into the container without the colors mixing and were able to place the materials into the container watching as they float in the appropriate layers.

Primary biological content area covered

This experiment will focus on densities and how different objects float in different substances. Weight is also a component as the different objects settle into the different layers based on their weight.


  • Oil
  • Water
  • Corn Syrup
  • Coins
  • Grapes
  • Cork
  • Test Tubes
  • Food coloring


1. Put one color food dye in the water and another color food dye in the oil.
2. Fill the container a third of the way with oil, a third with water, and a third with corn syrup.
3. The layers will separate (easily visible with the food coloring).
4. Drop a cork, a grape, and a coin into the container.
5. The different objects will settle in different layers because of the different densities.

Description of activity

Three layer float is an interesting experiment in which the students will be able to see how different liquids settle based on their densities as well as how objects settle based on their densities. First step is to place water, oil and corn syrup into a clear container and wait for them to settle. The three liquids will settle based on their densities and will make three separate layers. Next add in a coin, grape and cork and watch how they float in the different layers based on their densities. The students will be able to see that the objects with a heavier density sink to the bottom and the objects with a lighter density will stay at the top.

Lesson plan

  • We will start by explaining to the students how different substances have different densities.
  • Next the students will each take their materials (beforehand we died the water corn syrup different colors so the students will be able to see the layers more clearly).
  • No matter what order the liquids are poured into the tubes, the corn syrup will go to the bottom, the water will go to the middle, and the cooking oil will go to the top.
  • The students can observe through the different colors that the liquids separate because of the different densities.
  • Have the students form hypotheses about which layer each of the objects will stay in.
  • Next the students will drop three objects into the test tube, a cork, a grape, and a coin. Each object will float in a different layer of liquid.
  • The students should think and talk about how their hypotheses compare to what actually happened and with the layers of liquid and with the objects.
  • We will explain to the students that these objects float in different layers because of the density. A grape is heavier than a cork even though they may be the same size. The coin will float to the bottom, the grape will stay in the middle, and the cork will float at the top.

Potential pitfalls

  • Food coloring will mix if you shake the container too much. Liquids will still separate but identifying he different layers will be more difficult.
  • After making a sample and having it sit in the same position for about two days, the two colors mixed making it difficult to see the layers. Although this is not originally a problem, it may become a problem if the children want to use it later on after making them.
  • If the grape is put in last and is too big in relation to the cork, it will not be able to pass through to the layer it belongs.
  • Be sure to cut the grapes and the cork if necessary to fit in the container. If the objects are too big for the container, they may not be able to reach their appropriate layers because they will block each other.

Math connections

Although this activity does not relate to anything with math connections, it has a lot to do with physics. Densities throughout this project relate to the different weights of the liquids that we are using. Each liquid has its own density and we are able to show it through the different food coloring. Also, the grape, penny and cork each settle in one of the three different layers based on their densities. Students should know about densities because it is important throughout their lives because there are so many different densities in many different things they will encounter.

Literature connections

"What Is Density? (Rookie Read-About Science) By Joanne Barkan. Children's Press(CT)September 2006.

"Will It Float or Sink?" (Rookie Read- About Science ) By Melissa Stewart. Children's Press 2006.

Connections to educational standards

SI-2:9 Identifying, recording, and comparing characteristics of objects made of similar and different properties.

SI-2:12 Identifying, describing, and comparing the state of matter of solids and liquids.

Next steps

After the activity was completed, we showed the students a lava lamp. We showed them this because the liquid in the lamp looks similar to the liquids in the three layer float. We talked about how the different substances in the lava lamp float around because of the different densities and substance. Other things we did were put drops of food coloring into a transparent container of cooking oil, and the students saw how the food coloring stays in bubbles and does not spread to dye the oil like it would in water or the corn starch. Students can experiment with other objects around the classroom or outside and test hypotheses on which layer they think it will go to. To wrap up the experiment, we had the students complete a worksheet in which they matched the object with the layer in which it settled. This allowed us to see if they understood the experiment and it showed them what they learned by completing the experiment.


Of the three experiments that we have done so far for this class, the three layer float was my least favorite. Although it was my least favorite, I think it went well. The children seemed very interested when we first showed them the example container with the three different layers. It is definitely better if there is food coloring in the corn syrup because then the students can really see the difference in layers and the colors interest them. The experiment really challenged the students to think about the objects and the differences in weight and density because most students immediately jumped to the conclusion that the cork was the heaviest and after the experiment they realized it was actually the lightest. The students were excited to have something to bring home with them, as they were allowed to bring their test tube. It is important that students do activities in the classroom that they can then bring home with them. This prompts them to show their families and talk about the experiment and what they have learned. Learning occurs in the schools and should be emphasized and continued in the home. The one thing that was unexpected was that when the three layer floats are shaken too much, they will not return to their layers. We did not think about this in the first trial, but once we realized it, we told the other groups not to shake their containers. In the end the experiment was successful and was definitely a good visual to help children better their understanding of density and weight. -Molly

This experiment I found to be interesting but as Molly stated in her reflection I also agree that it was my least favorite experiment. I found that it was very simple and not that engaging for the students to be working on especially when the students were in 1st grade. I thought that it was an interesting project especially based on the fact that the students were so intrigued by the idea of that the liquids stayed in their same position no matter what way they flipped the tube. I found that they were most interested by the ideas of the penny, grape and cork floating in its own position. In general, I wish that this experiment could have had more interesting or fun ideas for the students to work on but there is nothing we can do about it now. I found that the three experiments we worked on were all different and interesting and I am glad that I was able to work on each of them with different students. The students are the key into these projects and can show you how to work the best with different projects. This experiment was successful for the students to be working on and in the end was engaging enough that the students enjoyed the day. - Katie

Our third and last experiment, three layer float, definitely did not turn out as I expected it to. When we completed the experiment with the students, it never seemed to work out as well as when we did it in the classroom ourselves. It was very important that each liquid layer was equal and if it wasn't the objects didn't float in the right layer and when we flipped it to its side everything would end up in one layer which didn't happen when we experimented earlier. Although the students were young and not familiar with the concept of density, a brief explanation from our group bettered their understanding and they were able to come up with reasonable conclusions as to what would happen when we placed our three objects (cork, grape, and penny) into the test tubes. As it was important for the liquids to be equal in the tubes, it was just as important for the objects to be the right sizes as well. If one object was too big, the other objects were not able to pass through, completely missing the point of our whole experiment. We luckily found this out quickly and were easily able to fix the problem. This wasn't as engaging for the students as it perhaps could have been. By using different containers that had a flat bottom and kid-friendly bottles for the liquids so they could do it themselves instead of having to watch us do it for them would solve this problem. Overall, the experiment ran smoothly. With just a few easy changes I think this could be a really great, engaging experiment that will really teach the students a lot about the subject. -Erin

Citations and links

While brand new ideas are very valuable and most welcome here, tried and trusted ideas of others will probably make up the bulk of the material on this site. It is important to respect the copyrights of others, and also to acknowledge their ideas. A full citation to published materials is essential and also useful. If there are online materials that would be useful to supplement your program, link to them from here.