Cracking the clues

Your pupils may have noticed that, when a pool dries up, it often leaves a muddy bed, which cracks into regular shapes (polygons) as the wet mud shrinks. Therefore, ancient mudcracks show us that the area where they are found must have been mud that dried out in the past. It must have been surface mud rather than mud laid down under deep water. So the cracks are key clues to the conditions in which the mud was laid down.
Polygonal cracking in natural materials is caused by shrinkage and the shrinkage is caused either by drying out or by contraction on cooling. By trying the Earth Learning Idea, ´Cracking the clues´, we can simulate shrinkage conditions that cause mud cracks in the classroom, and see the stages as they develop. The photo shows polygonal cracking which has occurred by contraction on cooling.
This is one of many Earth Learning Ideas in the Earth Energy category.

Is Geothermal power renewable or not?

Carry out three simple geothermal power simulations and from what you discover, discuss whether any geothermal power sources are renewable or not?
This is our latest Earth Learning Idea but have you tried ´Power through the window´ which investigates most power sources?
These are two of many activities in the Earth Learning Idea Resources and Environment category

Three Earth science teachers + no money + internet = amazing success!

As the graph shows, in the past two years, there has been a steady increase in the use of Earth Learning Ideas and more than 295,000 free activities have been downloaded from our website so far, (data only from November 2008, when Earth Learning Idea was moved to its current web host). Earth Learning Idea has reached 162 countries across the world. When the three team members had their first meeting in April 2007, they had no idea that, within three years, they would have spread the ideas across the world and have reached millions of children. Such is the power of good science and the internet!
There are more than 200 entries in the Keyword index and most Earth-related topics can be found. Please let us know if you cannot find an activity to help you teach topics listed on your science or geography curriculum; the ELI team will try to help - please contact us.

Igneous rocks and different crystal sizes

The latest Earth Learning Idea ´Why do igneous rocks have different crystal sizes?´simulates crystallisation from a melt at different rates of cooling. This activity can be included in lessons on the rock cycle to model the cooling and crystallisation of magma to form igneous rocks.
This is one of many activities to try when teaching the rock cycle. Search the ELI Keyword Index for more.