Monday, 12 October 2009

Make your own rock!

Have you tried this Earthlearningidea? 'Make your own rock' is an activity in which pupils investigate how loose sediment may be stuck together to form a 'rock'. To become hard rocks, most sediments need to be cemented together. Pupils will be able to demonstrate how 'rocks' are made by compacting and cementing loose sand, devise a fair way of testing the strength of their 'rocks' and be able to explain that the strength of the rock may depend as much on the cement that holds the particles together, as it does on the composition of the particles themselves.
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Hypocentre said...

Following a recent school accident involving plaster of paris you may want to extend a similar warning to that for cement dust and recommend gloves (and other precautions) when handling it.

Mary from New Mexico said...

Another approach to 'cementing' the rock is with salt. Place some sediment in a jar or beaker then add water followed by salt. Stir the sediment and water until the salt dissolves. This helps to show that sedimentary rocks are made from pre-existing particles and ions dissolved in the water. The water can then be evaporated and the salt will 'cement' the sand. You may either heat the sample to evaporate the water or just leave it in a warm place over a period of time.

Earthlearningidea team said...

The idea added by Mary above has been incorporated into 'Extension ideas' for this activity and will be published in the Earth Energy category on Monday 26th October.
Thank you Mary!