A couple of years ago, with the re-write of the AP Chemistry test and the increased focus on inquiry,I decided that I needed to provide my students with the opportunity, not just to review the labs we had done, but to put themselves in a situation that required them to think about what they had done and try to apply it to a new situation. Additionally, the College Board sessions at recent ChemEd and BCCE conferences have consistently indicated that students need to do a better job of justifying or explaining in their free response questions.
I was looking for lab-related questions that were relevant and doable in either a lab setting or a thought session. My experience as a high school mentor for the U.S. National Chemistry Olympiad (USNCO) team had exposed me to the myriad of released practical exams that were available for use by students and teachers, and many of those practical tasks were along the lines of topics that could be tested on the AP exam; additionally, and most providentially, they were all inquiry based! Since the scope of topics in our lab work is fairly well prescribed by the College Board, I decided to make a blended review that incorporated both the AP scope and the USNCO practical tasks.
Originally these Thought Labs or “Flash Labs” as they are sometimes called, were designed to be done from a thought perspective and not actually completed in the lab. In my class I choose two Thought Labs and divide the students into groups of three. In a class of 24 students this would give me eight groups of three; four groups of students would be assigned lab A and four groups would be assigned lab B. Each group would have about 10 minutes to work through their assigned lab, putting their results on a white board, a technique borrowed from the teachers using modeling instruction.1 After the 10 minute time period, each group gets 1-2 minutes to share out, presenting their answers and their justifications; this way everyone has an opportunity to share what they know, and as a class we get the benefit of a giant group think on two different lab topics. A copy of both labs is provided for all students, so they can make notes and take them home for more reflection time.
For those teachers working in a paperless school, an easy adjustment would be to post the lab handouts in an electronic folder that is accessible by the students and use it the same way. If you like more structure in the classroom you could present the tasks in a Power Point format and have the students work the problem in little 3-4 minute sections, calling on various students for their suggestions. Alternatively, most of these Thought Labs can easily be done as an actual hands-on lab during a 45-minute class period. The disadvantage of the hands-on approach is that you would only be able to review one lab topic in a class period.
No matter how you choose to implement the Thought Labs, the hope is that you’ll find them to be of good use. The following Thought Lab “Lime-A-Way” makes use of the full gamut of my goals for these lab-based reviews: it addresses a common lab theme (titration including indicators), provides students an opportunity to design an experiment and a chance to justify their decisions. It also imbeds equations that are still tested but are no longer a separate question.
Students have found the Lime-A-Way Thought Lab challenging because of the restricted equipment list. Their first instinct is to use a burette for a titration, but this is not part of the list; the restriction of equipment forces them to problem solve. With a Thought Lab, you can change the question by simply varying the equipment or the materials list. You can, as a part of the discussion, ask students to consider how their answers might change if you remove a certain piece of equipment or change an indicator.
Many of my students have commented that they felt this style of lab review is helpful by making them incorporate the skills they’ve acquired in our course labs while increasing their comfort level when they’re asked to synthesize what they learned in a new lab situation.
- Find out more about Modeling Instruction at American Modeling Teachers Association, http://modelinginstruction.org/