1. Scientific Method

2. What is the scientific method?
A logical way of solving problems
It enables scientists to organize their work

3. Steps of the scientific method
Make Observations/Define the Problem
Hypothesis
Experiment
Analyze Data/Form Conclusions

4. Define the Problem
A scientific problem is usually stated as a question.
Ex: Does the amount of water affect how tall a plant grows?

5. Hypothesis an educated guess
should be an answer to the question you posed as your problem

6. Theory A hypothesis that has stood the test of time
In other words, it is strongly supported by a variety of data collected over the years

7. Experiment – testing your hypothesis
Controlled Experiment – all variables are the same except the one being tested
A variable is something that you change while doing your experiment
Ex: If your variable is the amount of water, you may give some plants 1 liter of water every day, and other plants 2 liters of water.
A good experiment only tests 1 variable at a time

8. Variables: 2 kinds
Independent variable – the variable being tested – the one you change (amount of water.)
Dependent variable – the change that results from the independent variable. (plant height.)

9. Experimental Group
The group in which the independent variable is changed.
Once again, you only test 1 variable at a time.
If you want to look at growth in plants, test either amount of food, water, or light…not all 3 at once!

10. Control Group
The group that does not receive the variable being tested.
Used as a comparison

11. Constants
Constants are the factors that stay the same with all groups.
Example – If you are testing how intensity of light affects plant growth, here are some constants you would use since you will only be changing intensity of light:
Amount of food
Type of food
Species of plant

12. Validity
What should a scientist do if he/she doesn’t get the results they intended?
What are some ways to make an experiment more reliable/valid?

13. Dependent Vs. Independent Variables –
please see if you can pick out the dependent vs. the independent variables in each of these examples…
George wants to know if different colors of light will affect plant growth. He puts plants under different colors of light and measures their height for 2 months.

14. Independent Variable
colors of light
Dependent Variable
– plant growth

15. Dependent Vs. Independent Variables
Lucinda wanted to see if her goldfish released more ammonia when given tropical fish food or goldfish food. She divided her 20 goldfish into 2 groups and put them in separate tanks and fed each group a different food for this experiment. She then measured the ammonia content in each aquarium for 6 weeks.

16. Independent Variable –
Type of food
Dependent Variable –
Ammonia content

17. Dependent Vs. Independent Variables
Charles wanted to know if his aquatic elodea plants would grow better in warm water or cold water. He divided the plants into 2 different tanks with varying water temperatures. He then measured plant height and counted the number of plants for 4 weeks.

18. Independent Variable –
Temperature of water
Dependent Variable –
Plant height

19. Dependent Vs. Independent Variables
Sally wanted to see if tadpoles grow more quickly if given a protein supplement. She divided 100 tadpoles of the same age and species into 2 groups. She gave 1 group the protein supplement with their food and fed the other group food without the protein. Each week, she would count the number of tadpoles found at various stages of development until they were mature frogs.

20. Independent Variable –
Protein supplement
Dependent Variable –
Tadpole growth/development
Constants?
Control Group?

21. Theory A hypothesis that has stood the test of time. Example:
Darwin’s Theory
of Evolution
Young Darwin
Old Darwin

22. Scientific Laws Events that always occur in nature!
Example: Newton’s Law of Gravity

23. Now, please do this Quia activity!