Rocks and the Rock Cycle

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Eldest was interested in rocks, so I threw a quick session together on the rock cycle.

Arrival Craft
Using my trusty paper plates and split pin method (as used in the Mung Beans session to make a model of plant life cycles), we made a simple model of a rock cycle.

Gather Together
I had asked children to bring along a rock to identify if possible and a few did. I handed out spare rocks to anyone who needed one. Then we worked through an identify your rock table.
This was very easy to set up, but pretty intense to run! I handed out the sheets, pennies and nails (for the scratch tests), then ran around a lot helping people examine all the different rocks.
Using their answers and a table I found online, we made a guess at identifying all the rocks.

We were going to follow this with a game I found online called Ride the Rock Cycle. But, we were pressed for time, so we skipped that. I think we’ll pick it up next term.
I was excited to play!

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Break for drink and a snack.

Final Activity
Crayon Rock Cycle.
There are quite a few descriptions of this online, but I first found it here, on another home educator’s blog, there are also descriptions of sugar and chocolate rock cycles!
I handed out zip lock bags, pencil sharpeners and crayons. Everyone shredded crayons into the bags. This was our modelling of Weathering and Erosion.
Next we pushed the crayon sediment into the corners of the bags and squashed it by treading on it. This modelled Cementation and left us with a crayon version of Sedimentary Rock.

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The crayon version is a soft rock with large grains and visible layers. A great way to talk about Sedimentary Rocks.
Next we needed some heat. I filled a couple of mugs with boiling water and put them on a table, with grown up supervision, just in case. We put our crayon rocks back in their bags and dipped them in hot water three to five seconds. We took them out the water and (being reasonably careful) squished the soft crayon. This modelled the way rocks can be transformed by Heat and Pressure into Metamorphic Rocks.
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The Metamorphic crayons were harder and smoother than the Sedimentary crayons and some showed a lovely marbled effect.
Finally we refreshed the mugs of boiling water so they were good and hot. We put the crayon rocks back in their bags and put them in the water for a couple of minutes. Once the crayon was melted we removed the bags and left the crayons to cool.
This melting and cooling modelled the formation of Igneous Rocks.
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I was pretty pleased with this experiment. I think it really helped make the Rock Cycle easy to understand.
The children all seemed to have a good time!

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