Our Science Explorations with Rocks

Today we started researching rocks in Science. We used the laptops to explore these 3 links.
http://www.diigo.com/list/amoehlmann/science_rocks

What We Learned:
Up to 100,000 tons of rock fall from space to the Earth each year.
The largest Topaz crystal was found in Brazil in 1940. It weighted about 600 pounds.
Heat and pressure can change rocks-we call this metamorphic change.
Limestone is made from dead skin of sea animals.
Rocks have different hardness.
There are 3 types of rocks-igneous, sedimentary, and metamorphic.
Crystal is the hardest type of rock.
Most rocks are made from minerals.
Some rocks contain fossils.
The oldest rock is in Canada.