Rocks and minerals – porous and impervious.


Our rock cards. I wrote the name of the rock and the characteristics. Nicholas had to glue the correct pictures onto each card and classify them as porous or impervious.

Today’s lesson was the second time around on rocks and minerals. Last time we covered the three types of rocks. Today we covered two characteristics of rocks, uses or rocks and minerals, and went on a rock scavenger hunt. We also “made” a rock treat.

Two characteristics of rocks

After a review of the three types of rock and how they are made (igneous, metamorphic, and sedimentary),  and reviewing the rock cycle, we moved onto two characteristics of rocks: Porous and impervious. 

Porous rocks (like chalk) let water soak through them. Impervious rocks (like granite and slate) let water roll off them. 

I had cut out pictures of some rocks (slate, granite, marble, and chalk) and a picture of what the rock was used for. On 1/2 a sheet of paper, I wrote the name of the rock and a description. Nicholas had to, based on the description, glue the correct pictures onto the paper and then classify each one as porous or impervious. Once again, he had to tell me why he thought the rock was  in each classification. It is neat to hear him say, “Slate must be impervious if it is used for roofs. Otherwise people would get all wet and that would be silly.” Nice reasoning!

Uses of rocks and minerals

It is important to cover what rocks and minerals are used for. We talked about how rocks can be used in gardening, for decorating, to find minerals, to make markers so you don’t get lost on a hiking trail. It was equally important to cover what rocks don’t make – cars, boats, stuffed animals. At the end of the lesson he had grasped that just because something is hard like a rock doesn’t mean it is a rock.

Rock scavenger hunt

Just to make sure we were on the same page about the uses of rocks and minerals, I had Nicholas do a hunt around the house and yard for 5 things made of rock. He had to draw pictures of those 5 things. I had drawn 5 boxes on a piece of paper and in each box he drew a picture. It didn’t matter what the picture looked like, so long as it was something he could describe. He did quite well.

Rock treats

To reinforce our lesson, we made porous and impervious rock treats. Our porous rock treats were Rice Krispies. To make the Rice Krispies impervious, we covered them in chocolate. Then we ate!


We also played some great online games and clicked through more things about rocks.

Mineralogy 4 Kids

BBC Kids – we did the soil and states of matter activities.

ASU’s rock page

Kid’s Geo

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