Identify the independent variable...

We take 20 mice that were living in the same cage, and give 10 of the mice caffeine. Then we let all the mice try to get through the maze and time how long they take

Let's Review:

Brianna does an experiment to see which gets hotter: a metal bowl or a glass bowl. She leave them both out in the sun and measures the temperature.

a) What is the independent variable?b) What is the dependent variable?

An experiment has two groups:

The experimental groupThe control group

How do I decide if something is the

experimental group or the control

group?

You experiment group is the group you

are doing stuff to

Your control group is the group you are

leaving alone

Let's identify the experimental group:

+

Let's identify the control group:

+

WHY do we have control groups???

Control groups give us something to compare our experimental group to

If we didn't have a control group, we wouldn't know for sure why something happening in our experiment.

To be sure that pulling the cat's tail is the reason it bit us, we need to know that the cat would not have bitten us anyway.

Control group: Walk up to the cat without pulling its tail

A control group is not the same as a controlled variable

Controlled variables are what you call things you keep the same in both your control and experimental groupYour control group is the group you aren't doing anything to in your experiment

Let's practice finding the control group.....

Group 1 Group 2

We give one group sun, and don't give the other group sun

Group 1 Group 2

Which group is our control group?

You want to see if giving plants different amounts of water changes how much the plants grow. You give

one group of plants a lot of water, and one group of plants no water for 2

weeks. Then you measure to see how much they grow.

What is our independent variable?

What is our dependent variable?

What is our control group?

What is our independent variable?

What is our dependent variable?

What is our control group?

The group with no water

Sometimes you will have an experiment and need to make

a control group for it.

1) Identify your independent variable

2) make a group that does not get your independent variable

Asha wants to see if mice will drink less water if their water has salt in it. She makes a bottle of water with a lot of salt. Then she measures how much of the water the mice drink.

1) What is Asha’s independent variable?

2) What should Asha’s control group be?

1) What is Asha’s independent variable?

How much salt there is

2) What should Asha’s control group be?

Give the mice just water