1 class periods of 30 minutes each
The teacher puts pieces of potatoes in water and salt water. The students predict what is going to happen and try to name what makes this happen.
- Several potatoes
- knife to cut them with
- 1000 ml beaker of fresh water and 1000 ml salt water. It should be salty enough to float the potato.
- 4 250 ml beakers to pour the water into
- Blank paper for each student (It will be turned in when complete at the end of the discussion.)
Student Prior Knowledge
scientific method and the steps, the properties of matter
- Cut the potato into different sized pieces. Ask before you drop a chunk in if they think that it will float or sink. Help them to recognize the scientific method. Do not tell them which water is salty or that it is any different. Just label the beakers A & B. Try big chunks and small ones. The students should write down their predictions as you go. The students have been introduced to the word "Density". Try to get them to refer to their notes and find a word that would work.
- Now try mixing the water. Carefully pour 100 ml water into a beaker then carefully add the 100 ml of salty water. Ask the students to predict what will happen to a piece of potato now.
- Then pour 100 ml of salty water into a new beaker and 100 ml of water on top. The pouring must be done very carefully so it does not mix too much. The potato should hang in the middle. Ask them why.
- Have the students try to create a sentence using the word "Density" or a form of it, comparing the potato to the pure water, the salty water, and the mixed water.
Check over the sentences
Lesson Design by Jordan School District Teachers and Staff.