1. Steps scientists use to answer questions and solve problems
Scientific Methods
Steps scientists use to answer questions and solve problems

2. Solving a Problem Ask Question (Problem) Gather Information
State Hypothesis
Design Experiment
Make Observations
Collect and Analyze Data
Form Conclusions
Retest (validate)

3. Solving a Problem

4. Ask a Question How does fertilizer affect the growth rate of plants?
scientists notice something in their natural world
Example: Does fertilizer make plants grow taller?

5. Make Observations Gathered using the 5 senses
Record what happens during the experiment in your lab notebook
Use black or blue ink
The information you write down is called data
Example: My neighbors’ plants are taller than my plants. He uses fertilizer and I do not.

6. State a Hypothesis A suggested solution to the problem
Must be testable
Sometimes written as If…Then statement
Predicts an outcome
Example: If plants are grown using fertilizer, then they will grow taller.

7. Design an Experiment A procedure to test the hypothesis
set up an experiment testing different amounts of fertilizer on plants & measuring the growth (height) of the plants
must contain variables and controls
may have many controlled factors
can only change one variable

8. Design an Experiment Controls factors that are kept constant
not being tested!
examples: amount of water, type of soil, amount of sunlight, type of fertilizer
act as a standard of comparison
should not effect the outcome of the experiment

9. Design an Experiment Variables 2 types 1- dependent variable
The effect of _____________ on _____________
Design an Experiment
INDEPENDENT
Variables
2 types
1- dependent variable
what you measure in the experiment
unpredictable change: we don’t know how it will change until we do the experiment
graph on Y-axis
height of plants
2- independent variable
manipulated variable
predictable change: it only changes because we chose how it would change
the more trials… the better
graph on X-axis
amount of fertilizer
DEPENDENT
The effect of _____________ on _____________
Amount of Fertilizer
Height of Plants

10. Collect and Analyze Data
May be organized into charts, graphs, tables
2 types of data
Quantitative
Expressed mathematically numbers
Qualitative
Descriptive nature words, feelings

11. How’s a critter to choose?
Analyze Data
What does your data show
Graphs
line graphs
graphing data that shows continuous change
bar graphs (or histograms)
graphing data that is in disconnected groups

12. Examples of experiments
What’s the favorite drink of students?
we set up an experiment surveying students and asking which is their favorite drink :
dependent variable (Y-axis)?
number of students
independent variable (X-axis)?
type of drink
The effect of _____________ on _____________
Type of Drink
How many students chose it

13. Which drink do you like best?
number
Coke 1
Pepsi
Water 4
Iced tea
Gatorade 3 6
Bar graph! 5 4
number of students 3 2
Red Bull? 1
Coke RB
Pepsi RB
water
tea
Gatorade
type of drink

14. elevation (feet above sea level)
How does elevation affect temperature?
Line graph!
elevation (feet above sea level)
temp.
(°C) 30
500 25
1000 20
1500 15
2000 10
2500 5 30 25 20 18
temperature 15 10
1200 ft? 5
500
1000
1200
1500
2000
2500
elevation

15. Form Conclusions
Answer to the hypothesis based on the data obtained during the experiment
Check for bias
In order to verify the results, experiments must be
Retestedvalid!
Communicate results
Scientists publish work in journals

16. Any Questions??

17. Examples of experiments
How does exercise affect heart rate of 10th grade student?
we set up an experiment testing different lengths of time of exercise (minutes) on the heart rate of students:
dependent variable (Y-axis)?
heart rate
independent variable (X-axis)?
minutes of exercise
The effect of _____________ on _____________
Exercise
Heart Rate