Lesson Plan 10

Density.

SCIENCE

Audience: This is for second grader students.

Notes: This a lesson that compares the density of fresh water to the density of salt water. I will use the AIMS (Activities Involving Math and Science) activity called The Egg In Water. This experiment demonstrates that when salt is added to water it becomes denser, thus allowing an egg that would sink in fresh water to float or be supported by the denser solution. The egg will float halfway between bottom and surface or on top depending on the amount of salt added to the water.

Materials: Provide each group of 4 students with a large glass jar, water, salt, spoon, cup and an egg.

Procedures:

1. Carefully lower an egg into a container of water using a spoon. Note where it rests. Remove egg.

2. Add salt 2 t. at a time until there are 6 t. in the solution. Then add others 1 t. at a time .

3. After 9 or 10 level t. are added, a large egg will float. (Variables are temperature of the water, hardness of the water, and accuracy of the measurements.)

Hints:

1. Shaking the solution helps salt dissolve more thoroughly.

2. Also remove egg each time more salt is added.

Findings: A large egg will float on the surface of a quart jar 5/6 filled with water after 9 or 10 t. of salt are added. To make egg float lower in the water add fresh water (decreasing the density).

Lesson plan by Dale Hegler.

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