### Purpose

To observe rocks of various types and sizes and to record these observations through drawings.

### Context

This lesson centers on students making detailed observations of rocks. Through their observations, students will begin to develop an understanding that there are many types of rocks with a multitude of different attributes. Although students in the K-2 level are not yet ready to learn about the names of different kinds of rocks or the geological reasons for different rock formations, they are ready to understand that there are many sizes and shapes of rocks in our environment. They are able to recognize that our earth has sand, which is very small particles of rock; pebbles and small rocks that they may find in the dirt; and large mountains.

Read More### Planning Ahead

For background knowledge, you may wish to use these resources:

### Motivation

Begin by having students collect a variety of rocks. If it is possible, go for a rock hunt around the school. Each student can carry a bag for collecting the rocks that s/he finds. Later in the lesson, students will measure their rocks with paper clip chains, so you may want to ask students to include at least one rock in their collection that is big enough to measure in this way. If a rock hunt is not feasible at your school, have students collect rocks near their homes and bring them into school.

Once the group has collected a number of rocks, ask them to spread them out in front of them and look at the different types they have found. You might ask:

- Are all your rocks the same size?
- Do you see different colors in your rocks?
- Look at the different shapes of your rocks. What kinds of shapes do you see?
- If you pick your rocks up one at a time, do they all feel like they weigh the same?
- When you touch your rocks, what do you notice?

Let students walk around and look at the rocks that their classmates collected. Ask them to consider these same questions when viewing these rocks. Once students have had a chance to look at all the rocks, encourage them to talk about the variety of rocks there are in their class collection. To give them an opportunity to view even more types of rocks, have students use the Rocks student esheet to view the Rocks slide show, which provides a visual array of rock types. Students can click on any of the ten choices provided to view different kinds of rocks.

### Development

Taking students outdoors to view rocks in their natural surroundings is an ideal way to introduce the idea that rocks of various shapes and sizes are part of our earth. If it is possible, take your class outdoors and ask them to look for the different places they see rocks. To keep this lesson focused on the benchmark, ask them questions that help them consider the different rock sizes and shapes they see. (For example, there may be gravel in a parking lot, rocks large enough to sit on near a tree, and sand around a pond.) Since students have already begun thinking about some of the different attributes of rocks from their rock collections, this walk works well as a transition from thinking about rocks individually to thinking about them as part of our environment. If it is not possible to take an outdoor walk, try finding magazines and books with photographs of rocks to invite this kind of discussion.

Have students return to looking at their rock collections. Divide the class into small groups (groups of 4-5 work well). Ask each student to choose one or two rocks from their collection to bring to the small group. Allow students time to look at each others rocks. Give students magnifying lenses to allow for a closer inspection. Ask them to tell each other about their rocks. After they have had some time to describe their rocks to each other, lead a class discussion that challenges students to use more detail in their descriptions. As a practice exercise, hold up a pencil in front of the class. Ask them to describe the pencil. Help them develop more detailed descriptions by asking:

- What color is this pencil?
- What does this pencil have at its end?
- What does this pencil have at its other end?
- How long do you think this pencil is?
- What does this pencil remind you of?

If you hold up a second pencil that is slightly different in size and color, you can ask the same questions to help students recognize the value of using descriptions for comparing similar objects.

Now have students return to their small groups and give each student the My Rock student sheet. Ask them to complete items #1 and #2.

Next, give each group a box of paper clips. Show students how to link them together to make a paper clip chain. Ask them to make a chain that is long enough to fit around their rock. (If a student notices that the length of the last paper clip makes the chain a little longer than they need, but without it, it is not long enough, you can use language like, “Your rock is six paper clips and part of another around.” This introduces the concept of whole and part without going beyond their cognitive level.) Have students record their measurement on their student sheet (item #3), and then document their measurement pictorially (item #4).

At this point, it would be helpful to bring students back together for a large group discussion about how these measurements help to describe their rocks. Talk with students about why they think people measure things. You might ask:

- What do you think people learn when they measure something?
- How do you think measuring something might be helpful?
- What did you learn about your rock when you measured it with paper clips?
- Did you each use the same number of paper clips? (Have students compare their paper clip chains to give them an opportunity to see the many different lengths they needed for their different rocks.)
- When you look at one of these paper clip chains, what does it tell you about the rock it measured?
- When you look at these paper clip chains (use two from the class to demonstrate), what do you know about the two rocks they measured?

So far, students have made observations and recordings about the shape, size, color, and circumference of their rock. To help them think about weight, allow students the opportunity to use a scale for weighing their rock. Many types of scale will work for this exploration, and, if you have more than one kind of scale, students can “read” their rock’s weight in different ways. The goal of this exploration is for students to think about the fact that different rocks have different weights. Students can also experiment with weighing various combinations of rocks. If you do not have access to a scale, or are interested in making a scale from a few basic materials, see the Making a Scale teacher sheet.

To respond to item #5 on the student sheet, have students weigh their rock (the same rock they have been examining throughout this exercise). Now ask students to find rocks from their collection that are lighter than this rock, then rocks that are heavier than this rock. They should place these rocks in the appropriate spaces in the table provided for item #5. If students in your group seem ready for another challenge, you might ask them a few questions about the similarities and differences between the light and heavy rocks. You could ask:

- What is similar about your group of light rocks? Heavy rocks?
- Is there anything different among these light rocks? Heavy rocks?
- Are small rocks always light?
- Are the heavy rocks all the same color?
- Do the rocks with the same shape weigh the same?

These questions will help students think even more critically about various attributes and their relationship to weight. You can help students know that it is what a rock is made of that determines its weight, not the color or shape, etc. Since this idea involves concepts beyond their cognitive level, it is not necessary to spend much time discussing it, but it introduces students to the idea that when weighing a rock, some attributes are more important to consider than others.

Again, this measuring activity should encourage students to consider the concept of weight but not exact weight measurements. Students will practice with a measuring tool (a scale); perhaps have an opportunity to use more than one kind of scale, yet see that each has the same job—to measure; and they will begin to formulate hypotheses about their rocks, the scale, and the idea of weight. This strengthens the foundation of measurement concepts that will become more detailed and exact in later years.

Bring students back together in a large group. Facilitate a discussion to review their observations.

- What did you learn about your rock?
- What did you learn about the rocks in your group?
- How did you find out how big around your rock is?
- How did you find out about your rock’s weight?
- What words can you use to describe your rock (have them focus on the attributes they observed in this lesson—size, shape, color, etc.)?
- What description words could help someone else learn about your rock, even if they could not see your rock? How would this description help someone else know about your rock?

### Assessment

To help you assess what your students learned from this lesson, have them play a guessing game with their rocks and their student sheets. Have students work in pairs. With a few rocks displayed in front of them, ask that one student in each pair look at his/her partner’s student sheet and try to guess which rock the sheet describes. If a student is having a hard time guessing, his/her partner can make more detailed descriptions on the student sheet to give the student more clues. (This will challenge students to really make more specific and accurate recordings.) Students should be able to use paper clip chains and the scale to help them guess also. Once this first group of students has guessed the correct rocks, have the other partners take a turn at guessing.

While students are playing, walk around the classroom to help students brainstorm about ways they might clarify their descriptions. Refer to the questions listed throughout this lesson to reinforce the ideas of observation and description.

### Extensions

Students can dip rocks into paint or on an ink pad to make rock prints. You can make your own board game using rock prints to create the paths and real small rocks as the playing pieces. With a spinner or a die, you can play any number of fun games that would incorporate math. You can easily make the game one in which students learn more about rocks by making playing cards out of index cards or heavy paper. Each card could be a question that the player answers as s/he follows the path. (You can make this game yourself or allow students to create the game. When students make the game, they are practicing math and science skills and learning about problem solving as they determine what the rules of the game will be.)

For more ideas about extending learning about rocks, try these websites:

- Rocks Unit, from A to Z Teacher Stuff Network
- Kid Info: Geology
- KidsOLR: Geology
- Rock Hounds
- Think Quest: This Planet Really Rocks!