Tuesday, December 29, 2009

The Lab Test

It was Thursday morning. Students were antsy, anticipating the start of their two week winter break which would start on Friday. My period 4 class entered the room with their usual cheerful and social demeanor. The bell rang and I did my best to settle students into their seats for announcements and the ensuing lesson. Wanting to get their attention quickly, I announced "Today we have a test." Students began to frantically look at each other with that "he didn't tell us about a test" look. As the first student raised his hand to protest, I continued: "The good news is that you will work as a group of four on the test." The student's hand immediately retreated. Sighs of relief could be heard throughout the room. My explanation continued:

"The test you will be taking is a lab test. It is a test of your ability to use experimental skills to answer a lab question. This is a test which will allow me to assess your ability to conduct a laboratory investigation - to plan and to conduct a collection of procedural steps which lead to collected data and ultimately an answer to a question. Your goal is to determine the molar mass of butane gas - the gas released by this lighter. Your group must collect data in order to answer the question What is the molar mass of butane? There is equipment at your lab station which you are familiar with. Before you go to your station and begin collecting data, your lab group must first bring me a plan for collecting data and answering the question. Once approved, you may go to your station and begin executing your procedure. Your report is due at the end of the period. Get started."

As I sat down at the teacher's desk and prepared to observe and learn, students turned their chairs to form groups and quickly got down to business. Most lab groups recognized that they needed to answer the question by using the equipment and collecting data. Two lab groups asked "what is the formula of butane?" knowing they could find the molar mass quite quickly if they knew the formula. These were good book students who wanted to succeed at this test without being good lab students. In answering their question, I lied and said "I didn't know the formula." I then redirected their attention to the need to use the equipment.

Not knowing the magnitude of the task before them, another lab group squandered their valuable time in off-task behaviors centered around their plans for winter break. It's almost as though the mention of a lab was an indicator of recess. I sometimes wonder how many of my students view lab as recess? Maybe I don't want to know. Eventually, this lab group realized that they needed to get going.

A couple of lab groups had logistical questions - "Should we write the procedure in our notebook?" "Do we each need to write the procedure down?" Students in this class are accustomed to using a lab notebook to report on their lab findings. They are provided a purpose (or a question), told how to use the equipment and given minimal directions. They must decide what data to collect and how to record it and what to report in a conclusion. (See The Laboratory for a further discussion of this strategy.) Today, I had given them a sheet of paper on which to report their results. They were clearly not comfortable with the departure from the norm.

After about five minutes of brainstorming, organizing, and squandering time, all groups seemed to be highly engaged in the task of determining the molar mass of butane. It always amazes me how much more invested students become when a laboratory activity is called a lab test. Perhaps it was that the mention of the word test elevates the importance of an activity in the students' minds. Or perhaps the fact that I provided a challenge without providing a procedure captivated students and drew them in. Perhaps the elevated level of engagement can be attributed to both factors. Either way, it does seem that the level of student investment in a lab task is proportional to the degree to which they must take charge of the details.

Being near the end of a unit on gas laws, lab groups quickly realized they could use the gas collection tubes at their tables to collect the gas. Some groups recognized that the gas collection tubes were calibrated to measure the volume of a gas and that this volume could be used to calculate the number of moles of the gas. For these groups, the crux of their problem was finding a way to determine the mass of this volume of gas. Trying to stay as much in the background as I could, I watched enthusiastically from my teacher desk as students tossed out and discussed ideas. It gave me a great sense of joy to hear the students talking science. After much deliberating over this question, one student called out "You've really thrown us for a loop on this one, Mr. H!" I sensed from his tone that he was somewhat enjoying the challenge.

After about ten minutes of brainstorming, leaders seemed to emerge in a few of the lab groups. It was at this point that the students' lab test turned into a lesson for the teacher. One of the leaders - I'll call him Jim - was a student who has one of the lower grades in the class. Jim, who is considerably better at laboratory-based work than at seat work or book work, knew exactly what to do. While one of the lab groups (populated by several of my better book students) was trying to figure out how to get the gas out of the lighter, Jim was enthusiastically explaining to his group how to collect the gas in the eudiometer tubes, calculate the moles from its volume, and determine its mass by measuring the mass of the lighter before and after the delivery of the gas. The procedure seemed quite self-evident to Jim. Yet it took a while for his peers (the better students in the class) to catch up with his train of thought. While Jim would likely be the last student to correctly solve a gas law problem, he was the first student to solve a gas lab problem. Thanks to Jim's leadership, his lab group was the first group to have the procedure approved, the first group to collect the data, and the first group to submit the lab report.

Jim's group finished the activity early and Jim served as the proud representative to submit his group's report. I commented to Jim that he did a great job. I was sincere when I told him that he was probably one of my best lab students. He wasn't surprised when I told him he was a lot better with hands on, manipulative tasks than he was at book stuff. He acknowledged his strength and commented on how surprised he was to see his higher performing peers try to collect the gas from the lighter by holding it over the open-end of the gas collecting tube. I mentioned that there was a big difference between being book smart and being rubber meets the road smart. He chuckled and agreed. And then I thought out loud "schools probably aren't very kind to those who are rubber meet the road smart but not book smart."

I've given that interchange much thought over the last couple of weeks. I've contemplated my own courses. Do the courses which I teach favor those who can solve gas law problems but have no clue on how to do a gas lab problems? Is my assessment scheme weighted such that those who are willing to do and can do the book work will earn earn considerably higher grades than those who are weak at the book work but able to rise to the challenge when the proverbial rubber meets the road? Do I over-emphasize students' knowledge and understanding of science at the expense of their ability to do science? Are my courses unkind to those who are rubber meet the road smart but not book smart? In reflecting on these questions, I am afraid I need to revisit my current mode of operation.

Of course this story is about a lab test performed in chemistry class, and as such may seem a bit out of place in a blog devoted to a discussion of physics laboratory work. Nonetheless, the events which happened in my chemistry class on that Thursday morning can happen in any science class - physics included. The lab test is a great tool for assessing students' ability to do science. Students need to have opportunity to plan an experiment. They need to be asking questions about how to collect data, what data to collect, how to manipulate the data once collected, how to analyze the results, and how to report on the results. These are the types of tasks which scientists must perform. These are the types of tasks that students should be engaged in. When students are engaged in these tasks, science changes from a noun to a verb. Students begin doing science. Books are good; book problems are instructive; but eventually, the rubber must meet the road.

Tuesday, July 28, 2009

Calling All Bloggers!

Each month (or even more frequently) a new featured article is posted at the Lab Blab and Other Gab Blog. We are inviting high school physics teachers to participate. Do you have something to contribute? Have you experienced recent success with something new which others might be encouraged to learn about? Is there an aspect of scientific inquiry, development of physics lab programs, using laboratory notebooks, engaging students in the doing of science, or promoting scientific thinking which you would like to share. We are looking for teachers to compose short articles (500-1500 words) to be featured here on the blog. If you have something useful to say and would like to contribute to one of our featured posts, then please send your article (500-1500 words, Microsoft Word format preferred) to physicsclassroom@comcast.net. Enter Proposed Blog Post as the Subject Heading.

(Note: Submitted articles will not necessarily be used. If you would like to first discuss your idea with the Blog administrator before composing the article, then email a paragraph-length outline of the idea, describing the key points which you will make.)

Thursday, June 25, 2009


Welcome to Lab Blab and Other Gab - a blog associated with The Physics Classroom website. The role of this blog is to support physics teachers in the tasks of:
  • using lab notebooks as a lab tool in their physics classroom
  • developing and using inquiry-centered labs in their courses
  • getting students engaged in the same types of investigative tasks that scientists engage in
  • improving students' abilities to document their findings and to keep record of their learning
  • ... and anything related to high school physics labs, including comments regarding The Laboratory section at The Physics Classroom website.
Each month there will be a short featured article by a veteran physics teacher on one of these topics. The article will typically be a description of how a physics teacher incorporates lab notebooks, scientific inquiry or scientist-like activities into their physics classroom. The article will serve as a discussion point for that month. Visitors are welcome to respond and contribute.

The following teachers follow this blog:

Visit The Physics Classroom on FaceBook