This document discusses forming a hypothesis by making observations and inferences from experiments with variables. It explains that a hypothesis is a guess about the relationship between an independent variable that is controlled and a dependent variable that is observed but not controlled. Three examples are given where observations are made, inferences are drawn, and hypotheses are formed about how changing the independent variable affects the dependent variable.

1. Predicting and Forming a Hypothesis

3. Questions 1,2,3,4 #3 #2 #1 Hypothesis (guess) Dependent variable (no control) Independent variable (control) Inference Observation

4. Question 1

6. O 2 O 2 Independent variable? (control) Dependent variable? (no control)

7. Hypothesis IF oxygen level increases THEN fish population will increase. O 2

8. Question 2

9. IF the cola contains sugar, THEN it will sink The regular cola sinks The diet cola floats Variables Observation Independent variable (control): How much SUGAR in the cola Dependent variable: (no control) distance the cola goes up Hypothesis

10. Question 3

11. Plastic bag Pencil Variables Observation Hypothesis

12. Variables Observation Hypothesis Inference There is water in the plastic bag The pencil is sharp The pencil breaks the bag and the water pours out A GUESS If there are MORE holes in the bag, then MORE water will pour out. Independent variable (control): Number of holes in the bag Dependent variable (no control): How much water pours out Plastic bag Pencil

13. 10. Control 9. Width 8. Length 7. Chart 6. Graph 5. Hypothesis 4. Dependent Variable 3. Independent Variable 2. Inference 1. Observation Example Definition (words/pictures)