Beacon Lesson Plan Library

The Incredible Edible Rocks

Cathie London
Santa Rosa District Schools


As a culminating activity to the study of rocks, students observe three different goodies and compare them to the three different types of rocks, noting the similarities and differences.


The student knows that a model of something is different from the real thing, but can be used to learn something about the real thing.


-Venn diagram overhead transparency
-Paper plates
-Overhead projector
-Samples of igneous, sedimentary, and metamorphic rocks
-Venn diagram handout (see attached file)
-Prepared goodies


1. Ask three parents to make a batch of each goodie (see attached file for the recipes ).
2. Make a transparency of a Venn diagram.
3. Copy the Venn diagram for each student.
4. Have samples ready of each of the three kinds of rocks.


This activity culminates the study of the three different types of rocks.

1. Ask the students if they have ever eaten a rock.

2. Tell them that they will be eating rocks today.

3. Review orally the physical characteristics of the three different types of rocks—igneous, sedimentary, and metamorphic, showing examples of each.

4. The students review orally the definition of a model, citing examples and locating any in the classroom.

5. Divide the class into groups of three.

6. Give each group a paper plate with a sample of each goodie and a sample of each type of rock.

7. Each group studies the goodies, decides which kind of rock it models, and notes how the model is similar and different from the actual rock. They write down the similarities and differences on paper. The teacher circulates around the room noting the interaction between the various group members.

8. Each group then shares their results with the rest of the class. The teacher uses a Venn diagram on the overhead to model how to note and record similarities and differences using one of the goodie models and comparing it with the rock sample it models, ie. the rice crispy treat with the igneous rock--the treat is square, the rock is roundish ; the treat is soft and sticky, the rock is hard and rough, and so on.

9. The teacher hands out a copy of a Venn diagram and have the students pick another goodie and the rock sample it models and record three similarities and differences on their own Venn diagram just like the teacher modeled in step 8.

Now it’s time to eat! Each student gets a sample of each kind of goodie rock.


Use a Venn diagram to formatively assess the student’s ability to recognize similarities and differences between the goodie models and the actual rocks. Each student should be able to note three similarities and three differences. One side of the diagram should be labeled with the type of rock and the other side should be labeled with the model goodie.


Have the students make the recipes themselves during class time the day before the activity. This will show how the preparation of the goodie is similar but yet different than the formation of a type of rock.

Attached Files

The rock recipes and a Venn diagram.     File Extension: pdf

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