EARTH SCIENCE REVIEW

Experimental Design REVIEW

By Kelly Caflin

​Observations and inferences

​Observations - what you actually SEE, HEAR, TASTE, SMELL, or FEEL

• Qualitative- describes - color/texture/location/quality

  • example: the table is wood, the windows are across from the door

• Quantitative - tells how much or how many​

  • ​example: there are 10 tables.

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Inferences- what you THINK based on what you observed adn what you already know

• example: there are 30 chairs so there are probably 30 students, there are ​

Multiple Choice

Which is a qualitative observation?

• there are 3 kinds of footprints

• some footprints are bigger than others

• the animals were walking the same way

Multiple Choice

Which is a quantitative observation?

• there are 3 kinds of footprints

• some footprints are bigger than others

• the animals were walking the same way

Multiple Choice

Which is an inference?

• there are 3 kinds of footprints

• some footprints are bigger than others

• the animals were walking the same way

​Scientific Experiments

You must CHANGE SOMETHING

the one thing you change is called the independent variable

This will CAUSE the change in the experiment

This is what changes FIRST​

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You may only change ONE THING

if you change too many things, then the experiment is not controlled.

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Consider this example: I want to know if boys or girls are smarter. (I am changing the girls vs boys)

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I give the girls a math test with 10 addition questions. I give the boys a math test with 20 algebra questions. The girls score better.

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Can I conclude that the girls are smarter?​ No. I changed the gender AND the test. I don't know if the reason the girls scored better is because they are smarter OR if its because they have an easier test

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Multiple Choice

I want to know if a new plant food will help plants grow more. What should I change?

• the type of food I give them

• the amount of water I give them

• How much they grow

Multiple Choice

I want to know if a new plant food will make a plant grow more. I give a plant that usually grows 1 inch per month the old food. I give another plant that usually grows 2 inches per month the new food. The plant with the new food grows more in a month. Can I conclude the new plant food is better?

• Yes. The plant getting that food grew more.

• Yes, newer items are always more advanced than older items

• No, that plant always grows more naturally

Multiple Choice

The thing I changes is called the

• independent variabled

• dependent variable

• constant

Multiple Choice

I gave one plant the old food. I gave another plant the new food. I measured how much they grew. What is the independent variable?

• The amount of water that you gave each plant

• the type of food you gave the plant

• the amount the plant grew

Multiple Choice

The things you keep the same on purpose are called CONSTANTS. I gave one plant the old food. I gave another plant the new food. I measured how much the plant grew. What are two CONSTANTS that I need for this expeirment?

• The type of food and the amount of water

• the amount of water and the type of plant

• the type of plant and the type of food

Dependent Variables:

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You changed something. You were hoping that would affect or change something else.

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• I change the plant food--> the plant food changes the growth

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​Dependendent Variable

• ​the result

• the effect

• the data you collect at the end

• changes second​

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Multiple Choice

Which of these does NOT describe DEPENDENT VARIABLE?

• You make the change

• it changes as a result

• it changes second

• you collect the data from this change

Multiple Choice

What is the dependent variable?

I am testing if keeping the lights off will keep the room from increasing in temperature. The room starts at 18 degrees Celsius. I leave the light off for one hour. I then measure the temperature. Then I turn the light on for one hour and measure the temperature again . The temperature changed more when the light was on.

• if the lights were on or off

• the starting temperature

• the amount the temperature changed

​Practice:

​Key ideas:

Independent variable: you change it, it changes first, it is the cause

Dependent variable: it changes as a result, it changes second, it is the effect and what you write down

​Constants: you keep it the same to make a fair test​

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Multiple Choice

What is independent variable?

I want to know the best place to put the fan to make the room cooler. I put it in different places in the room and measure the resulting temperature.

• the temperature of the room

• the location of the fan

• the number of people in the room

Multiple Choice

What is dependent variable?

I want to know the best place to put the fan to make the room cooler. I put it in different places in the room and measure the resulting temperature.

• the temperature of the room

• the location of the fan

• the number of people in the room

Multiple Choice

What should I keep constant?

I want to know the best place to put the fan to make the room cooler. I put it in different places in the room and measure the resulting temperature.

• the temperature of the room

• the location of the fan

• the number of people in the room

Multiple Choice

What is the independent variable?

Does the thickness of a wire affect the current of electricity that flows through it? I attach a battery to a circuit with a thin wire and measure the current. I attach a battery to a circuit with a thick wire and measure the current.

• the type of battery

• the thickness of the wire

• the current

Multiple Choice

What is the dependent variable?

Does the thickness of a wire affect the current of electricity that flows through it? I attach a battery to a circuit with a thin wire and measure the current. I attach a battery to a circuit with a thick wire and measure the current.

• the type of battery

• the thickness of the wire

• the current

Multiple Choice

What should you keep constant?

Does the thickness of a wire affect the current of electricity that flows through it? I attach a battery to a circuit with a thin wire and measure the current. I attach a battery to a circuit with a thick wire and measure the current.

• the type of battery

• the thickness of the wire

• the current

Poll

What is the independent variable?

I have two water bottles. I want to keep my water coldest longest. One bottle is tall and thin. The other is short and fat. I put cold water in both bottles. I measured the temperature after 3 hours passed.

• the starting temperature of the water

• The temperature at the end

• The shape of the bottle

Multiple Choice

What is the dependent variable?

I have two water bottles. I want to keep my water coldest longest. One bottle is tall and thin. The other is short and fat. I put cold water in both bottles. I measured the temperature after 3 hours passed.

• the starting temperature of the water

• The temperature at the end

• The shape of the bottle

Multiple Choice

What should you keep constant?

I have two water bottles. I want to keep my water coldest longest. One bottle is tall and thin. The other is short and fat. I put cold water in both bottles. I measured the temperature after 3 hours passed.

• the starting temperature of the water

• The temperature at the end

• The shape of the bottle