Huge boulders, tiny grains of sand, silt, clay ~ all are made of rocks. Even though rocks are non-living, they can change in form both above and below the Earth's surface. In Science, we have been learning about how scientists classify rocks according to the way in which they were formed and we know that there are three main "kinds" of rocks: igneous, sedimentary, and metamorphic.
After using hand lenses to closely observe various properties of rocks (perusing through our classroom's three rock collections), we then turned our attention to two awesome virtual labs (Gizmos): Classifying Rocks and The Rock Cycle. We also researched our textbook for important information and also had fun with a Snickers candy bar correlation- be sure to discuss this at home! :-)
Here are some highlights of what we have learned:
- Igneous rocks form from other rocks that have MELTED. Melted rock below the Earth's surface is "magma" and melted rock that reaches the Earth's surface is called "lava".
- Mineral crystals form when lava cools IF they have time to form. Quickly cooling lava may have NO crystals- the longer it takes for molten rock to cool, the larger the crystals may form.
- Sedimentary rocks form when layers of sediments settle on top of one another and harden. Sediments are made up of soil, shells, bits of rock, and dead plant and animal matter It is in these rocks that FOSSILS are found! (Be sure to discuss our bread and gummy bear layering demonstration at home.) :-)
- Water, wind, ice, and gravity move the sediments that form these rocks. Over time, these particles settle in layers and press older layers together, which hardens them and forms rocks.
- Metamorphic rocks form from high temperatures DEEP inside the Earth. These rocks are also under a lot of pressure from the weight of the rocks that are above them. These "forces" can cause rocks to change their form into metamorphic rocks. The heat and pressure can even cause the mineral crystals in the rock to change! Chemicals in some rocks also cause other minerals to form. (Most rocks are made up of different combinations of minerals.)
- It is amazing that metamorphic rocks can form from sedimentary, igneous, AND other metamorphic rocks! Look at the diagram of the rock cycle at the beginning of this post to see just how interconnected the three types of rocks are.
- Students, what has been your favorite experience in class in learning about the Rock Cycle? Leave a comment to earn Behavior Bucks!
- Happy Science Sleuthing,