• Monitor and question students as they work in groups to break down rocks.

• Monitor students’ understanding that rocks are weathered and broken down into small particles by listening to responses to discussion questions.

• Monitor students’ understanding that weathered material is the parent part of soil.

• Observe whether students respond correctly to questions on student sheets and in discussions.

Activity 1, Day 1

Begin by asking students: “What do you know about rocks?” Display a KWL Chart (S-3-3-1_KWL Chart.doc) and record student responses to the questions under the K section of the chart. Then ask students to respond to the W section of the chart.

How Do You Make Dirt?

Tell students they are going to make soil, and then see how nature breaks down rocks. Divide students into pairs. Review with students safety practices to be used when conducting the investigation. Give each student pair two small rocks. Tell students they will read a Rock Concert Task Card (S-3-3-1_Rock Concert Task Card.doc) and follow the directions. They are asked to observe what happens to their rocks during the investigation. They will be asked to describe the size, shape, and color of the small pieces they get from their rocks using words or pictures. Note: Rocks such as sandstone, limestone, crushed granite, slate, and shale will work well.

1. Give each student pair a copy of a Rock Concert Task Card (S-3-3-1_Rock Concert Task Card.doc), a Rock Concert Observation Sheet (S-3-3-1_Rock Concert Observation Sheet.doc), and two small rocks. You can make rock tumblers from cups (S-3-3-1_Rock Tumbler.doc).

2. Review the Task Card for Part I with students and facilitate the activity by moving around the room and assisting when necessary.

3. Review each observation part with students if necessary.

4. When students have finished Part I and have recorded their observations, continue with Part II. When all students have had an opportunity to shake the rocks, they will return to the classroom and wait as you open the rock tumblers, then observe and record their observations.

Class Discussion

Discuss with students what they observed happening to the rocks as more force was applied to the rocks. Students should be able to respond with answers such as the rocks made sand or smaller pieces of rock. Ask students to look at the KWL chart and see if they have answered any of their questions they wanted to know or if they have more questions to add to the W section of the chart. Introduce the term weathering to students and explain to students they just demonstrated the weathering of small rocks using force and energy. Tell students as the rocks are weathered the minerals in the rock break down into smaller and smaller pieces. Refer to the KWL chart throughout the lesson and add or delete information when necessary.

Collect all the pieces of rocks (both large and small) made during the rock rubbing and tumbling and place in one large clear container.

Give students a damp paper towel. Tell students to wipe their hands and observe the paper towel. Ask, “What do you see on the paper towel?” Students may say “dirt.” If they say “soil,” accept this answer. People often use the words “dirt” and “soil” to mean the same thing. Tell students: “When rocks break down, they break down into smaller and smaller pieces or particles.”

Activity 2, Day 2

Display to students the large container of rock particles the students made during the previous lesson. Have students think how long it would take to fill the container with small pieces and how much force and energy it would take. Tell students that it takes millions of years for mountains to break down. Weathering is how rocks are broken down into smaller and smaller pieces. You may choose to watch a video such as https://www.youtube.com/watch?v=MFpCJsc_k64 that shows examples of weathering of rocks. Once the rocks are broken into smaller pieces they are moved over the earth. “Can you think of ways smaller pieces of rocks can be moved?” Students may or may not respond to these questions; this will be an introduction to the concepts of weathering and deposition. Lead them to understand that once the rocks have been broken by weathering and moved by erosion, they are deposited elsewhere. The deposited rocks mix with other materials on the way to making dirt. “When you rubbed the two rocks together and when they were in the rock tumbler, how was that like water eroding rock?” Students should make the connection that a powerful force is needed to break down rocks.

“Scientists examine rock material to find out what kind of rocks the material came from and what materials are in the dirt/soil. Scientists all agree on a scale to use when they are looking at these pieces of rock. Rocks are the nonliving parts in soil.” Show students the Rock Size Chart (S-3-3-1_Rock Size Chart.doc). Tell students the way a soil “feels” is called the soil texture. The texture depends on the amount of each size of particle or piece found in the soil.

• Sand, silt, and clayare names that describe the size of individual particles in the soil.

• Sand pieces are the largest particles and they feel “gritty or grainy.”

• Silt pieces are medium sized, and they feel soft, silky, or “floury.”

• Clay pieces are the smallest-sized particles, and they feel “sticky” and they are hard to squeeze.

“We are going to take our container of rock pieces and see if we can separate our container into groups by size.”

Layering Rock

In this investigation students will be placed in groups of four to six students. Students will work in groups to observe the size of the material found in the rocks that were crushed by students. Note: If there is not enough rock material crushed by students, you may take a hammer and place remaining rocks into a cloth bag and crush the rocks or you may use 2 cups of pebbles, 2 cups of gravel, and 2 cups of sand along with the crushed rock. You will need enough of this material for all student groups. Students are to follow directions on the Layering Rock Task Card (S-3-3-1_Layering Rock Task Card.doc) and independently answer questions on the Layering Rock Observation Sheet (S-3-3-1_Layering Rock Observation Sheet.doc). Note: Review directions to make sure students understand the activity prior to conducting the investigation.

After students complete the investigation, ask the following questions:

“What do you notice about the way the rock material acted in the water?”

“Do the different sizes seem to sink at different speeds?”

“Do you notice any layers in the bottles?”

“How would you describe the rock material that makes up these layers?”

“Are some layers thicker than others?”

“Is this dirt or is it soil?”

“Could you use this sample to grow something? How could we find out if this is for growing plants?”

Take a spoonful of this mixture and add a spoonful of sand, pebbles, and more rocks and place in a small container. Add a bean seed and place in sunlight and monitor for water. Have students observe the seed throughout this unit.

Extension:

• Students who are going beyond the standards can find other rocks in their area and break them down into smaller pieces, comparing them with the rocks in class. Are they the same or different?

• Students going beyond the standards can select a rock and write a story about the rock’s journey. Have the student write where the rock came from, how it was broken down, and how it traveled throughout its journey.

• Students who might need an opportunity for additional learning can look at rocks using a hand lens and find the largest pieces in the rocks. Then find the smallest pieces in the rocks.