Lesson 1: Caffeine Effects

Every day, many people drink caffeine. Coffee, tea, soft drinks and a number of other drinks put caffeine inside our bodies. How do you think that caffeine affects a person’s body? Try out your ideas on your friendly water flea.

Here are some definitions to help you in your investigation.

Water Flea - a very small aquatic organism that makes up plankton

Plankton - a group of organisms in water that provide food for other organisms

Substance - a particular kind of matter with like properties

Drug - a substance that changes the body or mind of a person

Caffeine - a natural drug

Stimulant - a drug that raises the level of activity in an organism

Depressant - a drug that lowers the level of activity in an organism

Affect - something that makes a difference to something else

Effect - a change that is the result of an action

Doing the science

1. Start the Water Flea Simulation by clicking on the “Simulation” tab.
2. You can use the Timer Counter on the left side of the screen to find the water flea’s heart rate or you can use a stopwatch.
3. To use the Timer Counter, click the “Start” button, then click the “Click Me” button each time the flea’s heart beats.
4. After getting in the rhythm of the beats, click the “Stop” button and the flea’s heart rate will be displayed in beats per minute in the space below the buttons.
5. Record this value (normal heart rate) and the gender, feeding status, and mass of the flea in Table 1 below.
6. Click the “Caffeine” button, then select the “Single Dose” button. Count and record in Table 1 the flea’s new heart rate. Click the “Clear” button.
7. Click the “Caffeine” button, then select the “Double Dose” button. Count and record in Table 1 the flea’s new heart rate. Click the “Clear” button.
8. Click the “Feed Flea” button and repeat steps 3 - 7. Make sure to record your data in Table 1.
9. Select a Male water flea and repeat steps 3 – 7. Make sure to record your data in Table 1.