Experimenting with Science

If you VARY something, you CHANGE it If you VARY something, you CHANGE it. You might VARY or CHANGE your hair!

You might VARY or CHANGE what you eat. On Monday, Wednesday, Thursday, and Friday, I ate pizza for lunch. On Tuesday, I varied from my usual diet and ate a hamburger for lunch.

Scientists VARY or CHANGE things to see what happens.

What does it mean to vary something? If we VARY it, we CHANGE it!

When scientists vary something… …we call that an experiment. …or a test. …or a trial.

For a trial to be FAIR, a scientist can only change ONE thing at a time.

Scientist wonder…hmm… Hmm…I wonder…

Scientists start with a question Hmm…I wonder… Does fertilizer really make a plant grow bigger, OR does Home Depot just want to take our money?

To answer this question, scientists will only change ONE thing, the amount of ____________!

The ONE thing that is changed, is called the INDEPENDENT VARIABLE.

INDEPENDENT means By itself All alone Just that one

All the plants start out exactly the same. Same type, same age, same size.

All the plants get watered the same amount.

Each plant is watered at 8a.m. and 6p.m.

But, ONE thing is VARIED…

One thing was changed on purpose!

The plants receive different amounts of FERTILIZER

Since the fertilizer is the one thing we changed on purpose, we call it the INDEPENDENT VARIABLE!

WE DID NOT CHANGE

The amount of water each plant received. WE DID NOT CHANGE The type of plant. The amount of water each plant received. The time the plants were watered. The amount of sunlight the plants received.

We CONTROLLED the water, sunlight, and the type of plants! That means we kept them the same.

They are the CONTROLLED VARIABLES! So the - plants - water - time - sunlight all stayed the same! They are the CONTROLLED VARIABLES!

SAME! We CONTROLLED them. We did not let them change at all. We made them stay the very SAME! We did not let them change at all.

Guess what happened to the plants?????????

The plants that had fertilizer grew taller and larger!

The growth depended on the fertilizer.

So, we call that growth the DEPENDENT Variable. The growth of the plant was the Dependent Variable. The growth depended on the fertilizer, the change we made on purpose.

The DEPENDENT variable… DEPENDS on the independent variable. It is measured or counted at the end of an experiment

How would a scientist write the hypothesis for this experiment? A hypothesis is an educated prediction about the experiment.

It is written as an If, Then Statement

If I add fertilizer to a plant, What is the other magical word in the hypothesis?

Then

If I add fertilizer to the plants Then…

If I add fertilizer to the plants, THEN the plants will grow bigger.