Saturday, September 25, 2010

The Back of the Room

At this time of the year (the first few weeks of school), I'm thinking a lot about the back of the room. Like most science teachers, it is one of my main objectives during the first few weeks to set the stage for the remainder of the course with regard to the role of lab. Part of the stage-setting process is that I get a little preachy about the importance of the laboratory and its uniqueness to the curriculum.

On the first day of class, I tell my students that "Science class is different than other classes because the room is bigger." I pause long enough for them to show those looks of confusion and perplexity; then I repeat the statement.  After repeating the statement, it is clear from their faces that they need and want an explanation. So I explain that the back wall of our classroom is not located behind the last row of seats like it is in their other classes. Unlike math class, history class and english class, the back wall of our science classroom is located a good thirty feet behind the last row of desks. Lab tables and lab equipment fill the extra 30 feet of classroom space. The activity that happens in that space is what makes science class different than other classes.

Then I explain that the room is bigger in science class because the subject of science is different than other subjects. Compared to their other courses, science is unique. It is this extra 30 feet in the back of the room that makes it unique. Borrowing a line from a colleague, I explain that the answers to our questions are found in the back of the room and not in the textbook. Every trip to the back of the room involves an effort to answer a question. The question must reign supreme in the mind of every student as they cross the threshold between where science is talked about and where science is done.

Herein lies the challenge: forming questions that lead students along a path of inquiry and result in a learning experience in the doing of science. For certain, not all questions are created equal. So what makes a good question? Here are some of my quick ponderings on the topic. I think that good questions share some of the following traits:
  1. Good questions are testable questions; the answers can be found within the lab environment. 
  2. Good questions are interesting questions; they engage students.
  3. Good questions are questions that are clear enough to guide (and replace) the procedure.
  4. Good questions are questions whose answers cannot be found in the textbook.
  5. Good questions emerge from students' own curiosities. 
This past week, we started what is perhaps my favorite back of the room experiences. I call the lab Improving Your Image. While the lab is definitely challenging, it is also one of my students' favorite back of the room experiences. When I watch students do this lab, I feel like science is happening. The question and the purpose that is presented to students is
Question: What is the mathematical relationship between the number of images formed by a combination of two plane mirrors and the angle between the mirrors? 
Purpose: To determine the mathematical equation that relates the number of images to the angle between two plane mirrors. 
As is my usual custom, I discuss the question and the purpose during the pre-lab session; students write the Title and Purpose into their lab notebooks as I quickly made last-minute preparations. To explore the question, I have purchased several inexpensive 1-foot square mirrors from a department store and have taped sets of two mirrors together at their edges using duct tape. I showed students the equipment and demonstrated how the angle can be adjusted. I also showed students a protractor that was available at each lab station. I then asked the class, "What will the procedure involve?" The question/purpose is clear enough to provide the answer to that question. Invariably a student is glad to volunteer the procedure. I then asked the class, "What data will you collect?" Once more, the question/purpose is clear enough to provide the answer to that question. Several hands lifted as students eagerly participated in the pre-lab. In effect that question that is posed at the beginning of the lab guides and even replaces the procedure. For the remainder of the lab, the question (and not a step-by-step procedure) will remain at the forefront of the students' minds.

Curiosity piqued during the pre-lab session as I asked the class, "Have any of you ever done this procedure in your bathroom?" This question got some odd looks, but the odd looks quickly subsided as several students responded with audible O' Yeahs. I asked a responder to describe how they have done this procedure in their bathroom. She explained how they have a mirror on the door of their medicine cabinet which opens up towards a second mirror on the wall. They can open and close the medicine cabinet door and adjust the angle that it makes with the wall mirror. If they place their face between the mirrors, they will begin to see varying number of images with a varying angle. The other responders grinned in agreement. Excitement built as more students recognized that they have done the same thing. I dismissed the students to the back of the room to begin investigating the question.

Students began adjusting the angle between the mirrors and counting the number of images that they could see. As I entered the back of the room, I heard a chorus of wow, cool, and ewww. Interest heightened as students begin to manipulate the mirror angle and observe the multitude of images. As the angle grew narrower, the number of images increased. The photo below illustrates the wowness of the lab. Seeing the multiple images of a single object as you scan the 360-degree panorama is a "this rocks" experience for students.


Students adjust the mirror angle and count the number of images. They repeat the count for a variety of angles, collecting sufficient data that would allow them to answer the question - to determine the mathematical equation relating the number of images to the mirror angle. On years in which I wish the challenge to be easier, I suggest angles of 180, 120, 90, 60, 45, 40, 30 and 20 degrees. And on some years I allow them to choose whatever angles they wish. I almost always follow-up the activity on the following class day with a JAVA simulation that models the formation and location of images for varying angles. (View applet exercise.)

This past week, I entered the lab a few minutes after startup. As I approached one lab table, I overheard three students talking like I've never heard them talk before. They were fully engaged in the question. A sense of enthusiasm could be observed in their voices as they were adjusting the mirrors, counting the images, and pondering the question. I tried to keep my presence unknown as I eavesdropped on their conversation. They were discussing how the mirrors were dividing up the space surrounding the apex into sections and an image was present in each section (except for the section the object was in). They were quite animated in their discussion; they used their arms to form angles and began to point out the image locations. One student began sketching in her lab notebook to illustrate the point she was trying to communicate. As their hypothesis developed, they changed the angle and recounted images in an effort to test it. I knew they were doing science. And I knew they were close to the answer when I heard them talk about dividing 360 degrees by the angle. I quickly left for fear that I'd be invited to help answer their question. They were making great progress and enjoying each minute of it; it was time to scram.

A few minutes later I approached another lab table where one of my students was content at working by himself on the problem. Needing a sounding board, he stopped me and remarked, "Mr. H, I've been thinking about this pretty hard ever since you showed us the question." I love ponderers. And I love to hear that phrase I've been thinking. He sounded out his hypothesis about what the equation was and then paused for confirmation from me. Looking at the data table in his lab notebook, I asked him "What does the data say?" With a classroom-wide grin, he said "The data and the equation fit perfectly." Case closed!

I've been reflecting this past week on why do I like this lab so much?  I believe the answer is that this lab, perhaps more than any of my other labs, demonstrates the power of a good question. If labs are to be done with purpose (and not with procedure), then the question must reign supreme in every student mind as they enter the back of the room. This lab demonstrates nearly every trait of a good question. It is testable and answerable. It clearly engages students. It is clear enough to guide the procedure. It does not lead to a verification experience where an answer found in a textbook is verified in the back of the room. Few textbooks (if any) ever discuss the topic; this answer must be found in the back of the room.

For me, two of the greatest challenges to making the back of the room experience scientifically authentic has to with good questions. There are certainly other challenges, but I immediately think of the challenge of ...
  • ... forming questions that are strong enough to guide students along a path of scientific inquiry towards an answer.
  • ... cultivating an attitude among and developing the ability of students to form questions that are testable within a laboratory environment.
Near the top of this post, I mentioned five traits of good questions. The one trait that is not exhibited by this Improving Your Image lab is that the question does not emerge from the students' curiosity. The question certainly conjures up curiosity, yet I was the one who presented the question. This year I will be making efforts to improve students' abilities to form good questions - the kind that can be answered in the lab environment. Once students gain confidence that answers can be found in the back of the room, then it becomes their turn to ask the question. Once students begin asking the question, the level of inquiry will be raised to the highest level. (See previous post on Using Levels of Inquiry in the Classroom.)

Cultivating this attitude of curiosity and developing this student ability to ask questions will be on my radar screen for the rest of the year. Stop back next month as I report on my first effort at improving student ability to ask a good question.

This month's article is contributed by Tom Henderson.  He has been a high school physics teacher since 1989. Tom currently teaches Honors ChemPhys (Physics portion) and Honors Chemistry at Glenbrook South High School in Glenview, IL, where he has taught since 1989. 

Tom has placed a teacher's guide for the Improving Your Image lab in the Laboratory section of The Physics Classroom website. He invites interested teachers to view and use the guide.

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