CU 2.04Sorting Rocks

1. 1

   Bring the tray to a table. Take out each rock and place it in a row.

2. 2

   Place two color cards and sort the rocks that match. Leave the rest aside.

3. 3

   Mix the rocks again. Place the rough and smooth cards and sort by feel, eyes closed for a few rocks.

4. 4

   Mix again and line the rocks from biggest to smallest.

5. 5

   On another day, show the steel washer. Press its edge firmly across a soft rock and wipe: 'The washer left a scratch. This rock is soft.'

6. 6

   Try the same on quartz and wipe: 'No scratch. This rock is harder than steel.'

7. 7

   Invite the child to test each rock with the washer and place it under hard or soft.

8. 8

   Check the hardness sort against the control card together.

What catches the child’s eye

• The pale scratch line appearing on a soft rock and the washer sliding off quartz without a mark
• Soapstone feeling slippery, almost like soap, under the fingers

Extensions, easiest to hardest

1. Try a fingernail scratch first: rocks a fingernail can scratch are very soft
2. Sort by two qualities at once, such as smooth and dark
3. Learn the names of three or four rocks in the set with three-part cards
4. Sort a bag of rocks the child collected outside