Do Now (while I check your homework) List the 6 steps of the scientific method (without notes) Write a hypothesis about the following question… How does temperature affect tropical plant growth?

Identifying Variables of a VALID experiment

4 Parts of an Experiment Independent Variable- the part of the experiment that is changed on purpose, The part the scientist changes. What is tested What is manipulated

4 Parts of an Experiment Dependent Variable- the part of the experiment that changes because of the independent variable. What is observed What is measured The data collected during the investigation

4 Parts of an Experiment Control Group- the part of the experiment that is used for comparison Normally the group that doesn’t get the independent variable.

4 Parts of an Experiment Constant- the part or parts of the experiment that do not change

For Example:

A rocket scientist was given a jigsaw puzzle A rocket scientist was given a jigsaw puzzle. He was able to finish the puzzle in 5 minutes. Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

Identify the variables in this investigation.

What was the control group? The Rocket Scientist Because the students’ times are being compared to the scientist’s time to complete the puzzle

A rocket scientist was given a jigsaw puzzle A rocket scientist was given a jigsaw puzzle. He was able to finish the puzzle in 5 minutes. Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

What was the independent variable? Ages of the students Different ages were tested by the scientist

A rocket scientist was given a jigsaw puzzle A rocket scientist was given a jigsaw puzzle. He was able to finish the puzzle in 5 minutes. Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

What was the dependent variable? The time it to put the puzzle together The time was observed and measured by the scientist

A rocket scientist was given a jigsaw puzzle A rocket scientist was given a jigsaw puzzle. He was able to finish the puzzle in 5 minutes. Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

What was the constant? The jigsaw puzzle was the same for the scientist and the students.

Another example:

An investigation was done with an electromagnetic system made from a battery and wire wrapped around a 6 inch nail. The 6 inch nail could pick up 10 paperclips. Different sizes of nails were then used. The number of paper clips the electromagnet could pick up was then measured using the different sizes.

Control Group: The 6 inch nail that could pick up 10 paperclips. This was used to compare with the different size nails.

What are the variables in this investigation?

Independent variable: Sizes of nails These were changed by the scientist

Number of paper clips picked up Dependent variable: Number of paper clips picked up The number of paper clips observed and counted (measured)

Battery, wire, type of nail What was the CONSTANTS? Battery, wire, type of nail None of these items were changed

One more:

100°C water will boil an egg 100°C water will boil an egg. The higher the temperature of water, the faster an egg will boil.

Control Group- 100°C Water Independent variable – temperature of water Dependent variable – time to cook an egg – Constant - type of egg

Last one:

The water temperature at 5 feet was 68°F The water temperature at 5 feet was 68°F. The temperature of water was measured at different depths of a pond.

Control group- water temperature at 5 feet was 68°F Independent variable – depth of the water Dependent variable – temperature Constant – thermometer

Designing Investigations

The greater the amount of soap in a soap and water mixture, the bigger a soap bubble can be blown. Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?

The farther a ball drops, the higher it will bounce. Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?