Biologist ______Date ______

Sponge Capsules: Scientific Method Lab

Pre Lab

1.  What is a controlled experiment?

2.  Define the following:

a.  Independent variable

b.  Dependent variable

c.  Control group

d.  Experimental group

3.  Why are hypotheses important to a controlled experiment?

Purpose – To develop a hypothesis, test a hypothesis, collect data, analyze data, and compose a lab conclusion.

Background – In the lab you will be given 2 gelatin capsules that contain sponge animals that are common toys usually labeled as “magic capsules.” The animals will grow when placed in water. Consider the following questions about sponge animals.

Does the temperature of the water affect rate of growth?

Does stirring the water affect the rate of growth?

Does the type of water, salt or sugar or tap, affect the rate of growth?

Experiment – Choose ONE question from the front and develop a hypothesis. Remember to state your hypothesis in a complete sentence and make sure it is testable.

Hypothesis ______

______

______

Materials – 2 beakers, water (plain, warm, salt and/or sugar), 2 sponge capsules (same color), spoons, stop watch.

Procedure –

1.  With a lab partner, place enough plain tap water in one of the beakers to fill it approximately 2/3 full. Fill the other beaker to the same volume with salt water, warm water, or sugar water. Label each beaker as either CONTROL or EXPERIMENTAL.

The CONTROL beaker contains ______water.

The EXPERIMENTAL beaker contains ______water.

The Independent Variable is ______.

The Dependent Variable is ______.

2.  Have your stopwatch ready to go. Place the sponge capsules in each of the beakers and begin timing. Every five minutes for 20 minutes, measure the length (longest portion) of each capsule.

Table 1. Length of capsules over time

Minutes / Length in
CONTROL BEAKER (cm) / Length in EXPERIMENTAL BEAKER (cm)
0 (length of capsule)
5
10
15
20

Lab Report – All in complete sentences EXCEPT for materials.

1.  Question and Hypothesis: What is the question? Then state your hypothesis.

2.  Materials: List the materials you used.

3.  Methods: Briefly describe how the experiment was conducted. I should be able to perform the same experiment as you based on your methods. Use complete sentences.

4.  Data – See Table 1 above

5.  Conclusion: Write a summary describing your results. Your conclusion should answer the experimental question and state whether or not your hypothesis was supported (correct) or rejected (incorrect).

This is also the place where you would make up suggestions for future research.
State at least one source of error and at least one thing you would change or do better next time