### Purpose

To demonstrate that simple models can be used to represent real world objects that are not easily brought into a classroom.

### Context

This lesson is designed to allow students to create a wave model using two different types of simple models. In early education, students need be introduced to the concept of models. It is particularly important that they be exposed to qualitative models. "Moreover, problem-solving studies have shown that qualitative reasoning is not engaged if students move too quickly into memorizing and applying formal laws." (*Benchmarks for Science Literacy*, p. 357)

The approach of creating, describing, and understanding qualitative models is critical because it is the type of learning that students will most closely relate to their experiences. "Because the prior knowledge and models students bring to their science instruction are themselves usually qualitative, qualitative reasoning is closely connected to that prior knowledge." (*Benchmarks for Science Literacy*, p. 357)

### Planning Ahead

It would be best, but not necessary, to use newspaper as a cover for desks so that spilled oil will be easier to clean.

### Motivation

Either read to students or have them read the second chapter of *Henry and Mudge and the Forever Sea* (by Cynthia Rylant, with pictures by Suçie Stevenson). An alternative is a suitable section from the book *Oceans* (by Seymour Simon).

Ask students:

- Have you ever wondered about water and waves?
- Who has seen waves?
- Where have you seen waves?
- Can we study waves here (in the classroom)? Can we bring a wave into the room?

Say to students, "*Sometimes we can't look at the real thing in the classroom so we make a model that we can use to study and learn more about that thing. Does anyone know what a model is? What are some types of models you've seen or made?*"

Discuss students' responses and perhaps make a list of their ideas on the blackboard or flipchart. Tell students that in this lesson they'll make some different types of models that will help them learn more about how waves behave.

### Development

In advance, set out several 9x13 inch baking pans, and several pitchers or measuring cups filled with water.

Break the students into groups of four or five. Have students fill a pan about half full with water. (Since fractions are still a relatively new concept to students, show them about where half way is so that they can better visualize the amount.)

Ask students:

- What is one way that we could make waves in our wave pools?

Allow students to make several suggestions. Some of their possible answers will include rocking or sloshing the pan, blowing on the pan, splashing with their hands. Allow students to explore these different ideas.

Ask students:

- One way you made waves was to blow across the surface of the water. Is there something in nature like this? What?
- This pan is an example of a model of waves in water. What are the different parts of the model?
- How is this model like real waves?
- How is it different?

Have the groups clean their area by emptying and clearing the pans. Give water, cooking oil, food colors, and an empty water bottle with cap to each group. Have students fill their bottles half full with the water.

Have students pick a food color that they like and have them add one to three drops of coloring to their bottles. The students should cap their bottles and tip them on their sides. Ask students:

- What have we added to our bottles?
- Does it look like a real wave? How?

Have students gently tip their bottles from side to side. Ask them:

- Does this remind you of a wave?
- How is this like a wave?
- How is this not like a wave?
- How "good" is our model?

Hold up a bottle of oil. Ask students:

- What will happen when we add the oil?
- How do you think the waves will be different?

Have students gently tip the bottles of oil from side to side. Ask them:

- Does this remind you of waves?
- How is this like a wave?
- How is this not like a wave?

Say to students, "*Now let us add the oil and see what it does to our wave bottles.*"

Using a funnel, have the students carefully add oil to their bottles. Move from table to table and help students make sure that the oil touches the very top lip of the bottle. Cap the bottles tightly for the students. Have students tip the bottles sideways again.

Say to students, "*Now tip your bottles from side to side. If you see any air bubbles, raise your hand so that I can help you.*" Remove air bubbles by slightly squeezing the bottle and re-capping or by adding more oil. Once again, students should tip their bottles from side to side.

Ask students:

- Does this remind you of waves?
- Does the model (bottle) look different from when we tipped it without the oil? How?
- How is this like a wave?
- How is it not like a wave?
- How "good" is our model?

### Assessment

Say to students, "*Today, we looked at two models for waves. What are some other models that we use to describe or understand things? I want you to think of one example of a model and draw a picture to share. Be ready to describe your model and its purpose.*"

Allow students several minutes to draw. Ask them to explain their examples of models.

### Extensions

Have students go to the Oceans Alive from the Boston Museum of Science. Once there, students should look at the representations of waves.

Ask students:

- How are the pictures different from the waves we created?
- How are the pictures similar to the waves we created?
- A picture can be used as a type of a model. How is a picture that is a model different than a model like the ones that we made? How are they the same?