Play around with the DIAMETER-OF-TUBE and other parameters. Do some systematic observations. Collect data. Try to draw some conclusions about how lumen size affects the process of absorption.

Try to answer the following questions:

1. Write a question about the impact of lumen size that can be tested with this model.

2. (For example, If we vary 'x', how will it impact 'y'?)

3. Make a guess about the answer to your question and state it in the form of a testable hypothesis (for example, larger lumen size will result in more/less absorption).

4. Design an experiment to test your hypothesis. Explain your experimental design.

5. Conduct the experiment and collect data.

6. Write your conclusions. Did your observations support your hypothesis? Can it be accepted or should it be rejected?