2.2: Lab 2 Procedures

PROCEDURE 1: DESIGNING A CONTROLLED EXPERIMENT

Equipment we’ll needed:

• 3 termites per group
• Brushes for handling termites
• One small cup for keeping termites at the table
• 2-3 pieces of paper
• Pens (different types, brands, colors, etc; each group need at least one BIC)
• Timer (you can use your smartphone or computer)

Last week, we watched a video of an experiment testing whether termites follow lines drawn by a pen. We recorded observations and built some comparative questions surrounding the behavior of the termites. Now that we have live termites, let’s take a closer look! Follow the procedure below and answer the questions on the Answer Sheet.

1. Revisit the comparative questions. These will guide the rest of the experiment we are about to design. Each group can either pick the same questions or revise them if they have thought about different questions they would like to answer today. We’re planning on designing two experiments today, so we’ll need two comparative questions.
2. Write both a null and alternative hypothesis that attempts to answer each comparative question. Remember, don’t worry about trying to make the hypothesis correct!
3. List the dependent and independent variables of both experiments and whether each one is continuous or discrete.
4. Make predictions using the independent and dependent variables and the hypotheses. Remember that predictions tell us what to measure and may take the form of an “If… then…” statement.
5. One of the most crucial parts of the scientific process is getting feedback. Before writing the methods, walk around to a few other groups and share your ideas. Maybe another group thought of something you didn’t initially consider! Feel free to change a variable or method based on the feedback.
6. Now we’re ready to describe the methods we will use to test our hypotheses. These should be complete and precise enough so that another person can read the instructions and carry out the exact same experiment. Some things to include in our procedures:

• The equipment needed (both amount and type).
• The number of termites to be used throughout the experiment or the number of times each termite will be used.
• For today’s experiments, each group should include 5 trials.
• How we will measure the dependent variable.

7. Before we carry out the experiments, we need to devise an organized way to collect data. Build a data table that includes the dependent and independent variables and the number of trials we will have. It may be helpful referring to last week’s lab for some examples of how to organize data tables.
8. Now carry out the experiments! Follow the methods exactly. Define roles for each group member so data collection is efficient and accurate. Group members may want to switch roles between trials or experiments.

Termite Handling Instructions

These little termites are fragile! Please be careful while handling them, and handle them as little as possible. Note: we are using the term “handling” broadly, but we should not be using our hands to hold, pick up, or move the termites. Follow the instructions below to avoid harming the termites during our experiments.

• Use the small brushes to handle the termites.
  • To pick up a termite, gently press the bristles of the brush down in front of it to allow it to walk onto the brush. Alternatively, pick up the paper towel or piece of wood with termite(s) and gently tap the termite(s) into the small cup.
• Tip the small cup over to gently drop the termites into the “arena” (paper with drawn paths/shapes).
• Once the termites are on the paper, let them be for the duration of the trial! Do not continuously move them back toward the path/shape drawn on the paper. Doing so would bias the results of the experiment and tire the termites or increase the risk of harming them.
  • Caveat: termites may venture off the paper altogether (though this is rare). We do not want to have loose termites escaping into the classroom, so gently put these termites back on the paper or into the small cup.
• If a termite is unresponsive or not moving, feel free to swap it out for a more active one.
• Limit using a given termite for two or three trials to prevent fatigue.
• Return the termites to the large bowl they were collected from.

Clean up/Disposal

1. Gently return the used and tired termites to the labeled bin.
2. Return all writing utensils to their matching locations.
3. Dispose of paper in the trash.
4. Return tray to the original location.

PROCEDURE 2: ANALYZING QUESTIONS & GRAPHS

After running the experiments and collecting data, the next step is to analyze the data to see whether there are differences between the independent variables. One of the more common statistical tests is a t-test. There are many online t-test calculators, but the t-test calculator by GraphPad is a great tool (there is also statistical software like Excel or R).

1. Use a t-test to test for differences between the independent variables for both experiments and report the results in the Answer Sheet.
   • If you’re using the GraphPad website, keep boxes 1 and 2 on the default settings, enter the data into box 3, and click Calculate Now in box 4.
   • Refer to the Introduction to determine where the results are statistically significant.
2. Now interpret and graph the results. Make two graphs, one for each experiment. Remember to include all the necessary components of a graph. Refer to the Introduction for instructions.

Remember that science is iterative. Whether or not your results are statistically significant or support your hypothesis, there are always more questions you could ask! After doing two experiments, what else are you curious about with the termites?

Oftentimes in science, things do not go as planned. This is especially true in biology where we collect data on live organisms, including humans! We may think we designed the perfect experiment, but then when we carry it out, maybe the organisms do not “cooperate” or behave expectedly, equipment does not work as planned, we run out of time, or the results do not give us the answer we had hoped for. Think through these options to answer the remaining questions in the Answer Sheet.