2.+Hypothesis

Step #2: Forming a hypothesis - Read the following instructions, then post a hypothesis under the cause and effect question.

I. When writing a hypothesis, think about what is expected to happen when the question is tested. Think about what has been learned in the research summary of the question. Then place the variables identified in the cause and effect question (Step 1) into an IF…, THEN … statement that describes how the independent variable will be **changed** and the dependent variable **measured**. The hypothesis does not give expected values or numbers that will be measured. But it does indicate a trend of increased or decreased values under certain conditions. Remember common variables to change are time, light, and temperature. Try to think of a sophisticated measurement for the change expected. This measurement may involve using probes in the science lab so plan ahead.

II. Here are some BAD examples:

If the sun shines for 2 hours, then the plant will grow 3.4 inches. Comment: Measurements are already known – why do the experiment? Measurements were reported in English units.

**If it is sunny, the plants will grow. ** Comment: This is way too obvious.

**If the volcano explodes, the climate will change. ** Comment: What exactly is being measured about the climate and what “change” is expected?

**I think the food will make the dog sick. ** No comment. This one is just bad.

III. Additionally, the hypothesis must express a valid cause and effect relationship that is testable scientifically. For example:

**If it rains tomorrow, then there are clouds in the sky. **

**If the driver exceeds the speed limit, then he may receive a ticket. **

**If I can find a ride, then I will attend the game. **

**If my car breaks down, then I will be late. **

<span style="font-family: 'Trebuchet MS','sans-serif'; margin: 0in 0in 0pt;">Let’s look at each statement. Statement 1 does not express a logical relationship between the If and then clause. Rain does not cause clouds, rather, clouds sometimes cause rain.

<span style="font-family: 'Trebuchet MS','sans-serif'; margin: 0in 0in 0pt;">Statement 2 does represent a logical cause and effect and could possibly be investigated if the controls were properly determined.

<span style="font-family: 'Trebuchet MS','sans-serif'; margin: 0in 0in 0pt;">Statement 3 & 4 are correct and logical statements, but do not lead to a scientific investigation.