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Lesson 27:
Let's Do an Experiment!
One Experiment,Two Theories
Atheoryis an idea.A theory predicts what will happen.
An experiment shows what happens.
BRIAN:Did you read about this experiment,Danny?
I fill a jar with water.
I cover the top with a piece of cardboard.
Then,I turn the jar upside down.
JENNY:Guess what will happen!
DANNY:I'm not sure.I think the floor will get wet.
Maybe you should do this experiment outside,Brian!
BRIAN:No,we can do it inside.I'm sure the floor won't get wet.
DANNY:Why not?The cardboard can't keep the water in the jar!
JENNY:Let's do the experiment and see what happens.
Brian has one theory and Danny has another.
We can prove who's right.
BRIAN:Great!We'll do the experiment and make observations.
That's called scientific method.Weird Mud!
This experiment shows two new words:liquidandsolid
What's a liquidWater is a liquid.
What's a solid?In this experiment,
you make something that's a liquid sometimes and a solidsometimes.
What do you needa bowl,a spoon,cornstarch,water
What do you do?
1.Put eight spoonfuls of cornstarch into the dish.
What's aspoonfulof cornstarch?
When you fill a spoon with cornstarch,you have a spoonful.
2.Add four to five spoonfuls of water
3.Mix the cornstarch and water together
4.Pour the mud into your hand.
5.Open and close your hand.What happens to the mud
What is happeningSome things dissolve in water.
Sugar dissolves in water.But not cornstarch.It only mixes withwater.
When you close your hand,you squeeze some of the water out.
The mud becomes solid.When you open your hand,the water mixesin again.
Now it is a liquid!What else can you do
Put some of the mud in a bowl.
Now hit the mud with your open hand.
In English,we say that you aresmackingthe mud.
What happens?Now do the same thing with water.
Are the mud and water the same when you smack them?
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