1. Let students know that today’s lesson is about designing, conducting and evaluating experiments. Ask students to brainstorm what steps are involved in an experiment?
1) Come up with a question to explore.
2) Make a hypothesis or prediction about the results of the experiment.
3) Determine the methods involved in conducting the experiment.
4) Acquire necessary helpers and materials.
5) Test the materials and the experimental design, as needed, before conducting the experiment.
6) Recruit subjects and reserve a venue, if needed.
7) Conduct the experiment.
8) Record findings.
9) Analyze the results/data.
10) Present findings.
2. Ask students to describe some experiments they have conducted. Ask students to discuss difficulties they encountered in the process, as well as some of the positive highlights of their experiments.
3. Explain that today’s lesson focuses on observing, designing and conducting experiments with living subjects (humans or animals).
4. Let students know that you will now be showing a video segment from the PBS program The Human Spark. This segment features an experiment with rhesus monkeys conducted by Yale Professor Laurie Santos and her students. Ask students to observe the steps involved in conducting this experiment.
5. Play Monkey See, Monkey Take. After showing the segment, ask students to list the steps involved in conducting the experiment.
a) Researchers A, B and C stand facing a monkey. Researcher A tempts a monkey by showing it two grapes.
b) The researcher hands the grapes to Researchers B & C (one grape to each researcher), who are both wearing short-sleeved white t-shirts and dark pants, with their hair in a ponytail.
c) When directed by Researcher A, Researchers B & C each place one grape on a skewer which is attached to a flat surface (paper, cardboard, Styrofoam or similar material.)
d) When directed by Researcher A, Researchers B & A place the grape skewers on the ground and then one researcher turns around, facing away from the monkey.
e) The researchers then stand still until the monkey has stolen a grape from one of the researchers. Researcher A films the event.
f) One of the researchers says “good” after the monkey has made its selection to indicate that the researchers can move from their testing positions.
6. Ask students to explain what the goal was of this experiment and what the researchers discovered. (Possible answer: The goal was to examine monkeys’ understanding of human perceptions and mental states. They discovered that monkeys were good at thinking about where eyes are pointed, but only in the restricted context of stealing food. The experiment indicates that monkeys have a “glimmer of awareness of others’ minds.”)
7. Ask students to describe what gave Laurie Santos the idea to conduct this experiment. (In previous experiments, monkeys had stolen food from her and her colleagues when they weren’t looking.)
8. Ask students to describe some of the ways that the researchers’ controlled for factors that might cause monkeys to approach one researcher rather than the other. (Researchers dressed in similar attire- white short-sleeved t-shirts, dark pants and ponytails. The researchers were both women, similar in height and wore eyeglasses. A third researcher called out the commands, so that each researcher did her action at the same time. Researchers stood the same distance away from the monkey. Researchers used the same sized grapes, skewers and paper/cardboard. Researchers A & B took turns turning around and switched positions.)
9. Discuss the experiment with the students and solicit their feedback about the experiment. Discuss the importance of controlling for external factors in order to reduce the variables that might impact the results. Discuss the following terms and challenge students to identify each type of variable in the Laurie Santos’ experiment.
- Independent Variables- changes in the experiment that are controlled by the experimenter (for example, having one researcher face away while the other faces the grape).
- Dependent Variables- changes that occur as a result of the independent variable (for example, the monkey steals the grape when the researcher turns away).
- Controlled Variables- Anything else that could impact the results of the experiment (for example, the clothing of the researchers, the distance of the researchers from the grape and from the monkey, etc.) These variables are held constant during an experiment.
10. Brainstorm ideas on how researchers could modify the experiment to gain more insight into the monkeys’ reactions. (Possible ideas:
- One researcher could turn her back to the monkey and then as the monkey approaches, turn back around to face the monkey.
- Instead of turning completely around, one of the researchers could just turn her head and face her eyes away from the monkey.
- One researcher could turn her body around, but keep her eyes focused on the monkey.
- The researchers could sit down.
- One researcher could close her eyes, as if sleeping, while the other researcher could keep her eyes open.
- Both researchers could turn away at the same time.
- One researcher could be positioned closer to the monkey than the other.
- Have both researchers turn their backs and observe the monkey’s reaction.
- The researchers could conduct the experiment in the presence of multiple monkeys and just have one researcher turn her back.)
- Introduce the next segment by letting students know that they will now be watching experiments conducted with children and chimps. Ask students to observe the similarities and differences between each experiment conducted for children and its corresponding experiment conducted for chimps.
- Play Humans vs. Chimps. After showing the video, ask the students to list the four different experiments highlighted in the video. (Hidden object under moving cup; object-dropping/ social skills experiments; hidden object under cup with pointing; light vs. heavy boxes.)
- Discuss each experiment, highlighting the similarities and differences between each human experiment and its corresponding chimp experiment. (Refer to the “Humans vs. Chimps Discussion Guide,” as needed.)
- Discuss the findings of the experiments.
- Hidden object under moving cup: In the video segment, the chimp selected correctly every time, while the featured child made some mistakes. However, according to the narration in this segment, when looking at the results of many trials with different subjects, the results of chimps and human children are similar at this task.
- Object-dropping experiment: This experiment examines the social skills of children and chimpanzees and found that both children and chimpanzees pick up an object that is out of a researcher’s reach and hand it to the researcher (without being asked to do so).
- Hidden object with pointing: This experiment explores whether human children and/or chimps are able to interpret a pointing gesture as a way to help the subject to correctly complete a task. The experiment shows that, although humans perform well at this task, chimps do not. Chimps do not appear to realize that when that the researcher is trying to help the chimp by pointing to a cup.
- Light vs. Heavy: This experiment explores human children and chimpanzees’ understanding of the concept of heavy and light. The experiment examines whether humans and chimps can use information gained by observing someone else moving an object to make a decision about which object would be easiest for them to move. The human children are able to successfully choose the lighter object, while the chimps are not.
5. Lead a discussion about the methodology used in the featured experiments. Include the following in the discussion:
- Discuss the importance of having a large enough sample size to draw accurate conclusions.
- Ask students to think about how they could modify the design of the experiments to provide the researchers with more information. Possible modifications:
- Hidden object under moving cup: Experiment with moving the cups different numbers of times and see how that impacts the results—for example, shifting the positions once, twice, three times, four times, etc.
- Light-heavy experiment: Have one child at a time observe the boxes being brought in to see if children might respond differently.
- Object-dropping experiment: Have two subjects at a time participate and observe how that influences the results.
- Hidden Object with pointing experiment:
- Have the researcher keep her finger touching the glass by the cup with the hidden object (in a fixed position) and see if that constant pointing effects where the chimp looks.
- Have two chimps perform the task at the same time.
1. Review the different experiments that you have discussed already. Let students know they will be designing and conducting their own experiments with human subjects.
2. Ask students to brainstorm questions they would like to investigate. Possible ideas:
- Do people prefer one brand of food, beverage over another?
- Do people prefer one type of chair/ desk, etc. over another?
- Does covering up one’s sight or smell impact someone’s taste?
3. Divide students into small groups. Ask each group to select a question to investigate and to design an experiment to explore that question. Ask the groups to share their ideas with you. Provide them with feedback on their designs.
4. Ask the groups to conduct their experiments, using other students, friends or family members as subjects. Ask students to record their findings, by writing up the information, videotaping and/or audio recording the session. Possible experiments:
- Beverage Brand Comparison- Pour one product (for example- Coke) in one cup and another brand (for example, Pepsi) in another cup. Bring in a subject one at a time and ask the subject to taste one beverage, then the other and to indicate his/her preference. Make sure to vary the order in which each brand is presented. For example, for half of the trials give the Coke first and in half the trials give the Pepsi first. (You could also use 3 brands- 2 known brands and a generic store brand)
- Taste test with nose plugging– Peel apples and pears and slice them into cubes. Blindfold the subjects and ask them to taste the food with and without their noses plugged.
- Chair selection- Select two chairs. Ask students one at a time to come into a room and sit down. Observe which chair each student selects. Variations: Have one “comfortable” and one less comfortable chair. Let the student know that someone else (another student, your teacher, the principal, etc.) will be joining both of you—Observe which chair he/she chooses. Observe whether the choices vary based on who else the student thinks will be coming into the room.
- Toy/Game selection- Invite a student in a room. Have several games available to play with. See which one he/she chooses.
5. After students have conducted their experiments, ask them to summarize their findings and present them to the class. Ask students to reflect upon the design of their experiments and to think about how they could modify them (for example, increasing sample size, changing the items used, varying the environment in which the experiment took place, etc.).
Proceed to Video Segments.