1. Types of Scientific Investigations
Different research questions require different types of investigations.
Descriptive Investigations
Comparative Investigations
Experimental Investigations

5. Descriptive Investigation:
Involves describing and/or quantifying parts of a natural system.
Example – observing cells under a microscope and diagramming what is seen.
Has a research question, procedures, and conclusion
Used when little is known about the topic
No hypothesis or prediction
Key words: Observe, describe, list, identify

9. Comparative Investigation:
Involve collecting data on collecting data on different populations/organisms, under different conditions (ex. Times of year, locations), to make a comparison.
Has a research question, possible hypothesis, procedures, and conclusion.
Can have independent/manipulated and dependent/response variables
No control / control group
Key words: Compare/contrast, similarity/difference, categorize

10. *Most scientific investigations you do in science class will be experimental investigations

12. Experimental Investigations Have Variables
Independent Variable – the part of an experiment that you manipulate or change
Dependent Variable – the part of an experiment that responds to the change you made. Measure it!
Control – the part(s) of an experiment that you want to stay the same all the time

13. Experimental Investigation:
Involves a process in which a “fair test” is designed in which variables are actively manipulated, controlled, and measured in an effort to gather evidence to support or refute a causal relationship.
Example- Testing the height of a ramp to determine how far a marble will roll.
All known variables have been identified
Has a research question, hypothesis, procedures, control, and conclusion
Has independent/manipulated and dependent/response variables
All factors can be held constant except the manipulated

14. Graphs in Experimental Investigations
Turn a data table into a picture
Show trends (patterns) in the data
Make results easy to see

15. Pie Chart (Pie Graph)h)
Shows percentage out of 100
Often used in polls and surveys
Colors and patterns differentiate data

16. Bar Graph Compares groups to one another
Uses rectangular bars or pictures
Colors and patterns differentiate data

17. Scatter Plot (Line) Graph
Data points connected by straight lines
Shows change in data (usually over time)
Line of best fit (curve) shows trend in data
Most of the graphs you make in science class are scatter plot graphs with a line of best fit (curve)

18. Labeling a Graph – an Example
Graphs have labels
Title – Distance-Time Graph
X-axis (horizontal, flat axis) - Time
Y-axis (vertical, up and down axis) - Distance
Number values – x-axis: 1,2,3 and y-axis: 10,20,30
Units – meters (m), seconds (s)
/ s

19. What type of Investigation Is it? (Practice scenarios)
Identify the type of investigation described and justify your choice.

20. Scenario #1
_____________ Investigation
You count how many prickly pear cacti are growing in a field and record the number of pads on each plant.

21. Counting Prickly Pear Pads is DESCRIPTIVE
•What is your research question?
•Do you have a hypothesis? Why or why not?

22. Scenario #2
_____________ Investigation
You take two boxes of breakfast cereal, extract the iron from both boxes and look at the differences in iron content.

23. Iron in Different Cereals is COMPARATIVE
•What data are you collecting?
•What are you comparing?
•Do you have a question?
•Do you have a hypothesis?

24. Scenario #3
_____________ Investigation
Using the same engine model, you test different types of oil to see which one keeps the engine lasting the longest at 50 miles per hour.

25. Oil Effectiveness at 50 mph is EXPERIMENTAL
•What is your variable?
•What are your controls?
•What is your hypothesis?

26. _____________ Investigation
Scenario #4
_____________ Investigation
A new star is observed in the Andromeda Galaxy. Observations and data are collected on this new star.

27. Andromeda Star is DESCRIPTIVE
•What kind of data can you collect?

28. Scenario #5
_____________ Investigation
Park rangers count the number of rattle snakes observed along a specific trail at different times during the year. They use this information to let campers know when it is safer to go off the path.

29. Snakes on a Trail is COMPARATIVE
•What is being compared?
•What is the independent variable?
•What is the dependent variable?
•What could be a hypothesis?

30. Scenario #6
_____________Investigation
You observe how the diameter of a splash changes as you drop a marble from different heights into a pan of water.

31. Splash Diameter is EXPERIMENTAL
•What are you measuring?
•What is the variable you are changing?
•What are your controls?
•What is the potential causal relationship?
•What could be your hypothesis?

32. Homework time!
Now….it’s time to do classify the three
investigations that were given to
you in class today. 