The scientific method

The Steps

• State the problem or question

• Form a hypothesis

• Plan and conduct an experiment– Record observations and data

• Analyze data

• Draw conclusions

Experiment Terminology

• Variables—anything that can change in an experiment– Independent variable– Dependent variable

• Two groups– Experimental group—receives treatment– Control group—does not receive treatment

An experiment Jose’s science fair project

deals with popcorn and how well it pops. He predicts that dry corn will pop better than moist popcorn.

Jose’s Experiment

a. State the problem.

b. Write a hypothesis for Jose to test.

c. What is his independent variable?

d. What is his dependent variable?

e. Name a variable that he should control in his experiment (a controlled variable).

Tree FertilizerAn experiment testing tree fertilizer selected two groves of trees. Grove one was given the fertilizer mixed with water once a week for 5 years. Grove two was given only water every week. The height of the trees were measured every month for five years.

What is theControl groupExperimental groupControlled variableIndependent variableDependent variable

Grove twoGrove oneWaterFertilizerTree growth

PheromonesA test was conducted to see which smell females prefer. 3 white t-shirts, one covered in deodorant, one used during a gym class, and one plain were smelled by 100 females. The females were then asked to chose the shirt they thought smelled the best. 52 picked the deodorant covered shirt, 35 picked the plain shirt, and 13 picked the gym shirt.

What is theControl groupExperimental groupControlled variableIndependent variableDependent variable

Plain shirtGym shirt & Deodorant shirtT-shirtSmell of shirtPreference of females

a) Take measurements of the distance objects fall, and the time it takes them to fall that distance

b) Draw a conclusion about falling objects.c) Larger objects take less time to fall than

smaller objects.d) Does the size of an object affect the time it

takes to fall?e) Drop a number of objects.

Arrange the following information in order based on the Scientific Method.

1. d) Does the size of an object affect the time it takes to fall? **Problem or Question**

2. c) Larger objects take less time to fall than smaller objects. **Hypothesis**

3. e) Drop a number of objects. **Experiment**

4. a) Take measurements of the distance objects fall, and the time it takes them to fall that distance. **Record data**

5. b) Draw a conclusion about falling objects.

Note: In this experiment, the hypothesis is incorrect. What should the student do next?