Controlled Experiments

In this experiment, what is the independent variable?

• Type of soil

• Water

• Plant growth

• Sunlight

What is a valid hypothesis for this experiment?

• No sunlight speeds up plant growth.

• Organic fertilizer makes plants grow faster.

• Direct sunlight makes plants grow faster.

• Sunlight speeds up the rotting of the plant.

Answer explanation

This experiment tries to answer if "sunlight affects plant growth"!

What are three valid independent variables for these experiments?

• Playing music to the plant

• Giving coffee to a plant

• Putting specific insects inside a box with a carnivore plant

• Putting a plant on direct sunlight

Answer explanation

All variables are valid except sunlight... the questions don't mention it all!

In this experiment, one gummy bear was put in different liquids to see if it would grow. Circle the independent variables (the variable that was changed for each pair of gummy bears).

Answer explanation

The different liquids are the independent variables! That is the thing you change.

In this experiment, one gummy bear was put in different liquids to see if it would grow. Circle the gummy bears of the experimental group.

Answer explanation

The experimental gummy bears are the bigger ones, or the ones on the right.

In this experiment, one gummy bear was put in different liquids to see if it would grow. Circle the gummy bears of the control group.

Answer explanation

The experimental gummy bears are the small ones that look the same, or the ones on the left.

In this experiment, plants were given different brands of fertilizer. What is the independent variable?

• Plant growth

• Sunlight

• Brand of fertilizer

• Water

Answer explanation

The only one that changes is the fertilizer. One plant even had no fertilizer at all!

In Dr. Redi's experiment, what is the dependent variable?

• If jar is sealed or not

• Temperature

• Spontaneous generation of maggots

• Material used to seal jar

Answer explanation

Redi wanted to prove that life comes from life. He proved that maggots don't just generate spontaneously from rotting meat.

In Dr. Redi's experiment, what is the independent variable?

• If jar is sealed or not

• Meat to rot

• Maggots

• Material used to seal jar

Answer explanation

Redi proved that maggots don't just generate spontaneously from rotting meat. For that, he played with sealing the jars or not, and with what material.

In this experiment, different liquids were put in the fridge to see which would freeze first. What is not a control variable for this experiment?

• Container

• Amount of liquid

• Type of liquid

• Temperature

Answer explanation

To see what liquid freezes faster, three things stay the same: the container, the amount of water, and the temperature!