Density - An Introduction

Therese R. Tobecksen St. Andrew the Apostle
331-155th Place
Calumet City IL 60409
(708) 862-4143


1. The student will review the concept of heavy vs. light.
2. The student will review the concept of sink and float.
3. The student will conclude that solid objects of the same size and shape can
have different weights and therefore different densities.
4. The student will conclude that liquids and gases can also have different

Materials Needed:

Clear flat pan of water, a variety of objects to investigate the sink and float
concept, a concrete canoe (or any object that students would predict would not
float but will), a pan balance, a variety of objects to test the concept of
heavy vs. light, three like size cubes of aluminum, brass, and steel for each
group, corn syrup, corn oil, one jar or beaker per group, three small plastic
cups or containers per group, large jar for "density jar", petri dishes, ball
bearings, glycerine, small scrap of wood, plastic bingo chip, rubber stopper,
steel washer, two one liter plastic bottles, mineral oil, paint thinner,
alcohol, helium balloon


1. Ask students to predict if concrete canoe will float. Test predictions.
2. Have students test various random objects on a balance to determine heavier
and lighter objects.
3. Have students test objects to see which sink or float.
4. Show equal sized metal cubes of aluminum, brass, and steel. Have students
make some predictions about their weights.
5. Let students discover that the metal cubes are not the same weights.
6. Show two petri dishes, one packed with ball bearings and the second one
loosely packed. Place on overhead and introduce the word "density".
7. Show bottles of corn oil, corn syrup, and water and invite comments about
texture, and thickness of fluids.
8. In small groups, allow students to pour small pre-measured quantities of
corn syrup, water, and corn oil to see that each liquid forms a separate
9. Show first wave bottle containing mineral oil and blue colored water. Have
students conclude that the blue water is more dense.
10. Show second wave bottle containing paint thinner and alcohol. Have students
decide which liquid is more dense.
11. Make a density jar. Into a jar pour corn syrup, glycerine, water, and corn
oil. See at what level steel, a rubber stopper, a plastic bingo chip, and
a wood chip will float.
12. Take out a helium balloon and lead students to conclude that the balloon
floats because the helium in the balloon has a lower density that the air
in the room.

Performance Assessment:

Show students a glass of ice water. Ask them if they think that the ice or the
water has a greater density.

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