This term our Science topic has been rocks and after analysing the properties of different types of rocks in the previous lesson, this week we have conducted an investigation into rocks.
In small groups, we were given some granite, limestone, chalk, sandstone and clay and we asked ourselves the following questions:
- Which rocks are hard and which are soft? Is there such thing as a soft rock? How can we tell which rocks are softer than others?
- Which rocks are durable and which are not so durable? How can we tell which rocks are durable?
- Which rocks are the most impermeable? Are any rocks permeable? How can we test the permeability of rocks?
- Which rocks have high density and which have low density? How do we find out the density of rocks?
After discussion about how we could answer the questions above, we decided to test the hardness of the rocks by rubbing them together in our hands and seeing if any grains come off in our hands. We tested the durability of rocks by scratching each rock with a ruler and seeing if we could leave a mark. We tested the permeability of each rock by releasing droplets of water onto each rock to see if the water would be absorbed or run off. We tested the density of rocks by placing them in beakers of water and seeing if they would float or sink.
We discovered that:
- Granite is hard, durable, impermeable and has high density
- Limestone is hard, durable, permeable and has high density
- Chalk is soft, less durable, permeable and has high density
- Sandstone is hard, durable, permeable and has high density
- Clay is soft, less durable, impermeable and has high density
To make comparisons between the different rocks, we had to make sure the test was fair so each rock was rubbed the same number of times, scratched the same amount and with the same approximate force, had the same amount of water dropped on it and placed in the same beaker with the same amount of water.
