Procedure:

1. Out of sight of students, fill two large transparent drinking glasses with warm water.
   
   
2. Stir the salt into the warm water in one of the glasses until the salt has dissolved completely.
   
   
3. Now have students gather around the table where the two glasses of water are. Do not tell them the water is different in one of the glasses.
   
   
4. Have students describe what they see in the glasses, and have one or two of them touch the outside of the glasses and tell you what they feel (heat).
   
   
5. Now have students tell you what they think will happen when you gently drop the egg into one of the glasses of water. (Most students will predict that the egg will sink to the bottom.)
   
   
6. Have students watch as you first drop the egg into the glass of unsalted water. (The egg will sink.) Ask students if they think the same thing will happen with the other glass of water.
   
   
7. Now have students watch as you remove the egg from the first glass and gently drop it into the second glass with the salty water. (The egg will float, not sink.)
   
   
8. Invite students to brainstorm why the egg floated in the second glass of water.
   
   
9. After a minute or two, have one student put his/her finger into the first glass of water (the water with no salt) and taste it. Then have the student put his/her finger into the glass of salty water and taste it. What is the difference?
   
   
10. Now have students guess why the egg floated in the salty water but sank in the water with no salt. (The salt in the water makes the egg buoyant because the egg is less dense than water.)