2 Jul 2015

The Nature of Science

In-Class Activity

Submitted by Lori Watson, Earlham College
Categories
Description: 

I do this activity as an introduction to the nature of science.  An object (not easily guessable) is put into a paper bag.  The job of the class is to figure out what is in the bag. At first, the students are simply shown the bag (sense of sight). Discussion (hypotheses) ensues on what could be in the bag.  I then walk around and shake the bag so students can hear what's in it (hearing). This results in more discussion, with some previous ideas being discarded. The bag is then passed around and students can feel (but not open!) the bag and also try to smell it.  Even more discussion happens as students try to agree on what is in the bag.  After they come to one or two ideas, I ask what else they could do (besides open the bag) to find out the answer.  If it is easily doable, I perform their experiment (for example, dropping the bag on the floor).  Finally, they come to their "answer."

And I end the activity.  Without opening the bag.  Ever.

We have a discussion (and come back to it throughout the semester) about how this relates to science (for example, reaction mechanisms).  Scientists propose an explanation based on the observable data. Additional experiments might result in refinement, or wholesale change, in what the proposed explanation is.  But, most often, there is no way to "know" the answer. We cannot open the bag.

Learning Goals: 

Students will reflect on the nature of science, including proposing hypothoses on the basis of observable data.

Students will constructively engage with the idea of not always being able to know an "answer."
 

Equipment needs: 

A bag with an object of some kind (not easily guessable, and not breakable or perishable works best). When I did it, I used a bunch of fake grapes from a home decore store with the stem removed, but many other objects would be possible.

Implementation Notes: 

I have done this as a near the begining of the semester activity in a first-year science seminar as a way to introduce science, and begin to have students think in less "science and math is about getting the right answer" terms. The key here really is to NEVER open the bag.  The students get increasingyl insistant, and will come to your office (I currently have rising seniors I did this activity with 3 years ago who STILL come by and ask what was in the bag).  I kept the bag on a a shelf in the clasroom the entire semesster.  Students referred back to it many times in our disccusions.

Time Required: 
20-30 minutes, or longer depending on the depth of discussion.
Evaluation
Evaluation Methods: 

Students were informally assessed throughout the semester by asking questions such as "how does this model relate to our paper bag?".

Evaluation Results: 

Students, while uncomfortable with the unknowing, understood the point of the excersise.  They didn't LIKE it, but were able to articulate how scientists might not be able to prove an explanation correct, but could change it in response to new experiements.

Creative Commons License: 
Creative Commons Licence

Comments

I will use this LO. What a great idea. I plan to do this in small groups; I will have 3 or 4 bags, with each group getting a different bag. But one of the bags will have a different object....

I used this in my first two classes today (and will use it in my 6 pm class tonight too). It went really well. I did it a little different. I just asked students what was in the bag. I apparently biased the experiment a little bit by using a DSW brown paper bag so I commonly got shoes as a starting point. But we quickly figured out it wasn't shoes. I had some interesting suggestions of additional experiments once we got passed the typical shape, drop and smell. One person suggested getting the bag wet to see if we could get it to conform to the shape of the object. I opted not to do that experiment as I need the bag the rest of the semester. Another suggested X-rays. Overall, I think it went really well. It got them intersted and they actively participated in my next demo, lightling water on fire. I look forward to taunting them with the bag the rest of the semester. Added bonus, I just sent an e-mail to my co-workers that said "Hey, the DSW brown paper bag that is stapled shut in the prep room is mine. Please don't throw it away." So, it won't just be the students that don't know what is in the bag.

I used this LO today in two sections of 100 students. Because it was a large class, I prepared four "identical" bags. I held up one bag and led a discussion, suggesting to them that they come up with experiments to do to determine what is in the bag. They quickly thought of shaking, dropping, and smelling the bag. Many students suggested that they wanted to feel the contents of the bag so the four bags were passed around. However, I only gave them about 90 seconds, and then "their NSF funding ran out" and they had to stop the experiment. So some of the students were able to report back on what the object felt like. One of the objects was sqishier than the other three and we decided as a class to "neglect that data point due to sampling error." Both classes voted on the contents of the bag, and they voted that it was a "scrub brush," while the contents of the other bag was voted to be "toilet plunger."

Each of my other two co-instructors now has one bag in their office, as do I. One student was very vocal at the end of the activity that she wanted to know when the class would find out if they were right. It's like she played directly into my hand. I said that the class had voted, but if they wanted to find out more, they would have to propose more experiments. I plan to bring the bag to class regularly.

I ended with this quote from the NY times:

"Science is not a body of facts that emerge, like an orderly string of light bulbs, to illuminate a linear path to universal truth. Rather, science (to paraphrase Henry Gee, an editor at Nature) is a method to quantify doubt about a hypothesis, and to find the contexts in which a phenomenon is likely. Failure to replicate is not a bug; it is a feature. It is what leads us along the path — the wonderfully twisty path — of scientific discovery."

It is week 2 of class. The bag has continued to appear in the front of the class before we get started. The students seemed to pay even more attention to it this week. Quite a few of them came up to hold the bag and squeeze it. There was some chatter about when they would find out. Quite a few thought I would tell them 'eventually' but there were also some 'he is never going to tell us' comments heard.

This LO has been great. I have even had a student say that they have come to every class this semester (something not true of their other classes) because they were affraid I would open the bag and they wouldn't get to learn what was in it.

Well, today we get to learn something new about the nature of science. Actually, a few things. First, we learn that sometimes stuff gets thrown away on accident. Apparently our new custodian decided that the bag was garbage and it got thrown out. This is extremely disappointing.

We also get to learn about funding agencies. My wife was not overly enthusiastic about the original purchase price of the item in the bag. She was even less thrilled when she learned what was happening. I don't think I am going to be able to get funding for repurchasing the same item. This is extremely disappointing. Fortunately, the bag that I used came from a shoe store. To repeat the experiment I need the same bag, so she will have to buy some new shoes. It's my only hope.

I used this LO as part of a trustee retreat last weekend and it went over well (even the short 2 minute version). I think it gave a good sense to the trustees of what active learning, think-pair-share, and in-class activities are. A colleague of mine (Deb Mashek, psychologist) gave me a link to an article which outlines a similar activity and also provides some more background and theory. It is designed for 2 50-minute class periods.  The Mind as Black Box: A Simulation of Theory Building in Psychology Not sure if that lnk will work if you aren't a subscriber; the full citation is "The mind as a black box: a simulation of theory building in psychology," by Carolyn Hildebrandt and Jennifer Oliver, Teaching of Psychology, 2000, 27(3), 195-197.

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