Lab 1 background

Steps in the scientific method

Observation

Question

Hypothesis

Prediction

            If ___________, then ____________

Design and experimentation

Experiment and record and analyze data

Draw conclusions

May have to revise hypothesis

Control group

            what you compare the experimental group(s) to

Experimental group

            Has one variable that is different than the control group

            This variable is what you are studying in the experiment

Control variables

            things that are constant between the control and experimental groups

Independent variable

            what you are testing for in the experiment

            the thing that is different between the control and experimental groups

Dependent variable

            readout at the end of the experiment

            what you test for at the end of the experiment

Replicates

            You need to repeat the experiment to ensure the results are accurate

Either do the experiment a few times or have different people do the same experiment

Example

Observation

            Different wavelengths of light affect growth of plants differently

Question

            Does pH affect color of flowers?

Hypothesis

            The pH of soil determines whether a flower is pink or purple

Prediction

            If the soil pH is below 7, then the plant will produce blue flowers

Design experiment

            Independent variable – pH of soil

            Dependent variable – color of flowers

            Control group – plants grown at constant, high pH

            Experimental group – plants grown at pH less than 7

            Controlled variables – amount of water, properties of soil, type of pot used

Record and analyze data

            Record pH and color of flowers

Draw conclusions

Section 1.1

            Answer questions

Section 1.2

            Assign one student as a time keeper.

The other students will be doing exercise and then holding their breath.  All of the students will be doing the exercise.  This is because we want replicates.

How do you determine how many replicates you have?

            First, determine how long the students can hold their breath without exercise.

                        This is the control.

            Then, the students will exercise for 1 minute and then hold their breaths.

            Then, the students will exercise for 5 minutes and then hold their breaths.

            These are the experimental groups.

            What is the independent variable?

            What is the dependent variable?

Section 1.3

Set up one beaker with just water and one beaker with water and salt.  Put them both on a hot plate at the same time.

When you weigh out the salt, make sure that you put it on a piece paper and not directly on the scale.

Check the temperature at which they boil.

            What is the independent variable?

            What is the dependent variable?

            How do we determine how many replicates we have?