Hardness. Prepare the objects listed above in advance.
Take each object separately and describe it.
Say: I wonder if (the name of the object) is hard. When we say the object is hard, we mean that when I scratch it with another sharp object there is no sign left on it. It is very difficult to leave traces on it. If the object is hard it means it is resistant to permanent shape changes. Do you think the (object) is hard?
Let's make a hypothesis. I think it is hard (not hard).
Let us conduct an experiment in order to prove or disprove out hypothesis. We will need a coin for that. Take the (object) in the left hand and the coin in the right. Make sure your hands are in front of the baby's face so he can see well what is happening. Say: let's scratch the (object) with the coin. Do that. Say: let's observe now. What do you see? Do you see any lines or scratches left on the surface of the (object)?
Yes, we can see them (No, we can’t trace any scratch). It means the object is soft (hard).
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