Week Fifty: Density

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October 21, 2015 by WittyLibrarian

densityProgram Title: Density

Target Age Range: Tweens, Grades 4-6

Program Length: 90 minutes

Brief Description: Learn about the density, and make an amazing, multi-layer density tower.


Clean bottle or jar, with cap or lid

Vegetable oil

Food coloring

Alka-Seltzer tablet or Fizzy Tablets


Clear glass or jar

Pasta noodles, cooked


Baking soda

2 20 oz. bottles of (brown) soda

2% milk

Tall, clear containers (we used water bottles, but bud vases might work better)


Light corn syrup

Dish soap (blue or green)

Olive oil

Rubbing alcohol

Lamp oil

Turkey basters

Cost: $$ 50-100

Advanced Preparation:

Program Outline:

  1. formulaIntroduction and explanation of Density. Density – A Simple Explanation on The-science-mom.com, The Indianapolis Public Library Kids’ Blog’s Post on Density – Buoyancy, and Density For Kids on Activewild.com all provide excellent explanations of the concept of density. 

2. Invisible Soda Demonstration

3. Dancing Spaghetti Demonstration

4. Lava Lamp Demonstration

5. Density Tower experiment


We prepared one soda bottle beforehand, so kids could see the effect of mixing milk into soda. We also started a bottle of soda and milk during the program, and we checked the progress periodically throughout the rest of the program.

Rather than adding food coloring to the water, we used colored noodles to make them visible as they danced.dancingpasta

We performed the experiment as described, and the kids found it to fascinating.

  • Density Tower experiment

We primarily based our Density Tower off of Seven Layer Density Column on Stevespanglerscience.com, but we also consulted both Rainbow Jar on Playdoughtoplato.com and How to Make This Amazing 9-Layer Density Tower from Things Found in Your Kitchen by Gabrielle Taylor on Science.wonderhowto.com

Each kid made their own density tower, but they all did it together, one ingredient at a time. We showed the kids all the ingredients of the density tower, and asked them which ingredient should be first, second, etc. When the correct answer was given, we would pass it around the room for kids to add to their column. We gave each kid a turkey baster to use to add their liquids to their towers. It was important to try, if at all possible, not to touch the sides of the container as the liquid was being added. While useful, the kids found the turkey basters hard to use.

For containers, We used water bottles for our density tubes, although a narrower tube would have been ideal. Straight, narrow bud vases might be a better option if offering this experiment again.

Additionally, as a visual aid, we gradually filled a larger model Density Tower with each liquid, so kids could see what theirs was suppose to look like. For our model tower, we used a large, straight  vase.


Rainbow Pasta by Gimme Some Oven on Tablespoon.com

Density – A Simple Explanation on The-science-mom.com

The Indianapolis Public Library Kids’ Blog’s Post on Density – Buoyancy

Density For Kids on Activewild.com

Invisible Soda on Stevespanglerscience.com

Dancing Spaghett on Stevespanglerscience.com

Bubbling Lava Lamp on Stevespanglerscience.com

Seven Layer Density Column on Stevespanglerscience.com

Rainbow Jar on Playdoughtoplato.com

How to Make This Amazing 9-Layer Density Tower from Things Found in Your Kitchen by Gabrielle Taylor on Science.wonderhowto.com

What we would do differently:

For the most part, this program worked very well, and the kids were very engaged in both the demonstrations and the main experiment. We would suggest having turkey baster practice before starting the Density Towers. The use of the baster was a necessity, but most kids had never used one before and were unclear on how they were best used. Perhaps have them practice moving water from one glass to another might be a useful task to prepare them for the rest of the liquids that are used in the density tower.

Adaptation for older/younger audience:

This program is a solidly tween-age program. We do not think it would work well for a younger audience, due to how precise one must be when adding liquids to their Density Towers. Teens would most likely find the activity slightly too juvenile for them.

This program would, however, be an ideal Family program. With guardians present helping kids pour and assemble their liquids, the project should work smoothly, and a slightly younger age group could participant in the experiment.

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