Water Pressure (Oceans)

Objectives:

• Students will discover that there is more water pressure on the bottom of the ocean than at the top.
• Students will learn that the high pressures of the deep ocean may affect the types of plants and animals that can grow there. (They have studied adaptation in the desert portion.)
• Students will predict what may happen when the nails are pulled out of the carton.
• Students will record what happened in the experiment.

Materials:

• empty 1-quart milk carton
• 3 identical nails, ruler, empty margerine tub
• cup or other container
• 9 X 13" baking pan
• water

Procedure:

1. Open the entire top of the milk carton, then push each of the 3 nails through the cardboard on one side of the carton so they are in a column (see diagram). Make sure that the bottom nail is at least 3 inches above the bottom and all the nails are at least 1 inch apart.
2. Lay the ruler down the middle of the pan so that the 12-inch end of the ruler is touching one end of the pan.
3. Place the empty margarine tub upside down in the baking pan at the 1-inch end of the ruler.
4. Fill the milk carton with water all the way to the top. Have the students try to predict what will happen when the nails are pulled out. Will the water coming from each hole travel the same distance or will some jets travel farther than others? Talk about a few predictions, then have each of them write down their own prediction next to a drawing of the experiment.
5. Pull all 3 nails out of the milk carton at the same time and then slowly pour water into the milk carton so that it's always filled.
6. As the water squirts out the nail holes, watch to see how far each jet goes.
7. Ask the children to tell you what just happened. Did it match their predictions? Why did the bottom stream squirt out farthest? What might this tell you about the pressure changes the deeper you go in the ocean? How might this affect the animals? Do you think the animals in the higher level could travel deep in the ocean? What might happen?
8. Draw and explain what happened in the experiment.
9. Explain that there are three distinct zones in the ocean. According to our experiment, what is one way these zones are different?

Evaluation of Learning:

1. Did the student record in their experiment notes that the pressure on the bottom of the milk quart was greater than at the top? Did the student look puzzled when comparing this experiment to the ocean?
2. Listen to the students' answers to procedure number 7. Did they say that the animals had to adapt to the pressure?
3. Did the student draw the carton before the nails were pulled out? Did they write a prediction before the experiment?
4. Students will write what happened in their notes. Did they draw a picture of the experiment in action?

Reteaching Strategies:

• Take a picture of the water streaming out of the carton. Having a picture to refer to, may be easier to observe than a milk carton full of quickly drained water.
• Draw a diagram with arrows pointing in the direction of pressure for an extra visual explanation.