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Unknown Object Lab - Teaching the Process of Science

Todd Duncan (duncant@pdx.edu)
Last modified 2/18/03

This lab provides a simple way to illustrate the key features of the scientific process, suitable for almost any grade level. It’s also a good ice-breaker at the start of a class, to get students working together.

Core components of the scientific method include making observations about some part of the world in order to seek answers to questions, formulating hypotheses or theories to explain these observations, and performing experiments to generate additional observations that help refine the theories and zero in on the best answer to the questions. Scientific knowledge is always based on such observations and experiments, and a theory can be disproved by new knowledge but is never “proven” with absolute certainty because we always observations of nature always have the final say.

In this lab, the question is very simple and well-defined: What’s inside the box? Small groups of 3-6 students are provided with sealed boxes containing various objects. Each member of the group takes a turn at holding the box, shaking it, listening, etc. in order to gain information about the object(s) inside, without opening the box to see inside. A recordkeeper for each group records observations made as the box is handed around, in a 2-column format: 1) Properties they think describe the object (metallic, plastic, size, number of objects, etc. 2) Guesses - what is in the box? For each guess, record next to it the confidence in the guess on a 1-10 scale (10 highest).

Also ask the groups to record notes on the following questions, for later discussion:

1. What methods do you use to try to figure out what the unknown object is?
2. How certain are you that you know what the object is? How does this level of certainty change over the course of the exercise? This activity is a model for how your beliefs about what's true can change on the basis of evidence, so it’s useful to become aware of this process of changing beliefs.
3. What is the most convincing evidence for you?
4. How do you convince someone else that your guess is correct?

Encourage the students to reach a consensus within their group about the contents of the box . When they've reached a consensus or have decided they can't reach one, ask them to write down their best guess(es). After 5-10 minutes with one box, rotate boxes and repeat this process until every group has had a chance to experiment with all of the boxes.

Discussion
It is important to make the connection that this activity is a model for all of science - everything we do in science has a parallel in this activity, and anything we know about the world through science is known through a process like this. Answers in nature are not in the back of the book - we have no direct link to “truth” but have only our observations to formulate the best answer we can. This exercise gets at many of the things important in science: problem solving, testing knowledge claims, and persuading others that your theory is the best one given the observations so far. It also shows how your beliefs can be changed by new information: try to use this process as an analogy to how we learn and how science works in the real world. We always have limited information, have to devise experiments to figure out things without ever being able to “open the box,” or “look up the answers in the book.” Every answer in a science book was obtained by a process of investigation, of devising clever ways to make nature reveal some of its secrets, which is analogous to your struggles with the boxes (think about astronomy, particle physics, etc. where it's very clear that we can't see inside directly).

Notes on question 1 from past classes:
• how well it fits inside box
• weight
• sound of hitting side of box
• how much it can move in the box, how fast it moves when tilted
• whether there is a difference in movement in different directions (speed, amount, or sound)
• process of elimination plays a big role here--point out that they tend to guess familiar objects that most households have...relate this to the fact that scientists pursue the most likely explanation first

Question 2:
Did anyone have the experience of being absolutely certain they knew what was in there, only to find that it was something different? Did anyone think that figuring out the object was hopeless, but then suddenly have a flash of inspiration? If you were certain, did you have trouble convincing others in your group that you were right? Statements of others in the group affect your own beliefs. (For example, if one person comes up with a good theory and is confident of it, others find it difficult to generate alternative theories, unless a clear piece of evidence is noticed that contradicts the original theory).

Questions 3 & 4:
• most convincing when you test the idea yourself (as opposed to just hearing someone tell you what is inside)
• majority rule tends to play a role
• the more unique the sound (the more common possibilities can be eliminated by the sound), the more certain you are of a guess (for example, a soda can has a very distinctive sound)