Materials:
* 3-5 different types of rocks (smooth, rough, hard, soft)
* A nail or a small metal object
* A pencil or a piece of chalk
Procedure:
1. Observe: Look at the different rocks and try to guess which ones might be harder than others.
2. Test: Carefully try to scratch each rock with the nail or metal object.
3. Record: Note which rocks you were able to scratch and which ones were too hard.
4. Repeat: Try to scratch the rocks with the pencil or chalk.
Results:
* You'll notice that some rocks are easily scratched, while others resist scratching.
* Rocks that can be scratched with a nail are generally softer than rocks that can only be scratched with a metal object.
* Rocks that can't be scratched at all are the hardest.
Explanation:
This experiment demonstrates the concept of hardness, a property of materials that describes how resistant they are to scratching or indentation. Different rocks have different levels of hardness due to their mineral composition and structure.
Variations:
* You can test the hardness of other objects like glass, plastic, or metal.
* Use a Mohs Hardness Scale to identify the specific hardness of the rocks you tested.
This experiment is easy to perform and can help kids learn about rock properties in a fun and engaging way.