1. Explore What happened to the glass rocks? Why did this happen?

2. Our subject for today: Weathering

3. California Science Education Standards: 6 IE 7.h: Identify changes in natural phenomena over time without manipulating the phenomena. 6 IE 7.a: Develop a hypothesis.

4. Objective 1 Students will know that certain natural phenomena (such as physical and chemical weathering) change the Earth ’ s landscape over time.

5. Objective 2 Students will be able to explain how physical and chemical weathering changes the Earth ’ s landscape, and compare physical weathering to chemical weathering.

6. Weathering The Earth ’ s surface changes constantly. One way that the Earth ’ s surface is transformed is through weathering.

7. Weathering Weathering is the gradual breakdown of rock into smaller pieces by natural processes such as precipitation, wind, plant growth, and temperature change.

8. Weathering Rock can undergo two kinds of weathering: Physical and Chemical

9. Physical Weathering Physical weathering breaks rock apart into smaller pieces that retain the characteristics of the original rock.

10. Explore What are some examples of physical weathering in our environment?

11. Physical Weathering Another type of physical weathering is called abrasion. Abrasion occurs when tiny rock fragments carried by wind and water scrape across the Earth’s surface. These fragments act like sandpaper, pitting and polishing objects in the environment.

12. Explore What happened to this rock?

13. Chemical Weathering Chemical weathering happens when minerals in rock interact with chemicals found in water and air. These chemicals cause the rock to break down.

14. Explore What happened to these rocks?

15. Explore What type of weathering has affected this rock?

16. Explore What type of weathering affected this rock?

17. Explore What type of weathering did the glass rocks undergo?

18. Assessment Questions How does physical weathering change rock? How does chemical weathering change rock? What kind of weathering could produce a smooth, worn surface? Fill in your Venn with at least three examples in each section.