Can high school students truly drive their own lab experience? I’d say after enough time and exposure, they can. This is what led me to develop a version of the Carbonate Project to have students perform after the AP Exam. This experience requires students to do some research, execute previously performed lab techniques, and identify an unknown substance.
A number of years ago I stumbled across Emily Dudek’s 1991 Journal of Chemical Education article, A Carbonate Project - Introducing Students to the Chemistry Lab. In this article, she discusses a four-step lab procedure that allowed her students to identify an unknown alkali metal carbonate. As I read through the four processes she identifies (a chemical reaction with mass loss, a gravimetric analysis, a collection of gas over water and a titration), I realized that all of these procedures were processes that my students had experienced between chemistry and AP Chemistry. I began to explore if my students could do this project, without any explicit instructions from me.
laboratory design Procedure time: > 90 minutes Time required:After introducing the assignment I provide the rest of the class period for research and planning and then two more class periods for experimentation. Students who need time beyond these three periods are encouraged to meet with me after school or at another time which works in their schedule.
I present my students with the following proposal.
Student-Led Project
Your goal over the next few class periods will be to identify an alkali metal carbonate. To do it you will need to perform (at minimum) two experiments, using techniques we have worked on in class, in order to get enough information to verify the identity of your substance.
You should work in a group of 2 for this task.
As your common task for the second semester, your research group will submit two forms of documentation. First is a research and planning document. Second is an abstract discussing your experiment along with all data collected. These will be submitted for review via google classroom.
Research Proposal
Your research proposal should include the following:
Like Ms. Dudek’s project, I keep my carbonates to Li, Na, and K, but omit that information for the students. Each pair of students will receive an unknown sample labeled with a number. They need to submit a detailed proposal to me explaining the two lab techniques they plan on using, a detailed procedure and materials list for each. I also require citations of 5 resources. Once the plans are approved, they may begin executing the procedures in the lab. I require two experiments to ensure that their identification is verifiable. I encourage having a third procedure available in case one of the original two provides inconclusive data. I also offer guidance with regard to available materials, minimizing waste, and student safety.
See the Supporting Information to access the document I provide students outlining the expectations for their Abstract and Project Reflection. (Readers must log into their account to access. Not a member? Register for free!)
The students genuinely enjoy the experience. As typical high achievers they relish being “right” and knowing the answer. It is valuable for them that sometimes the experiment doesn’t work as expected. Some students get beautiful data on their first go around. Others have a hard time initially and need to complete further trials or need to change an experiment entirely. Often students want to “leave out” their inconclusive trials, which leads to many vibrant discussions on how there is no bad data, just data we haven’t understood yet.
When students have enough evidence to identify the carbonate, I have them write an abstract including their identification, explaining the process used, and including the evidence collected. Students turn this in collectively. The more valuable analysis, is the reflection students are asked to write individually. They address frustrations, successes and things they would do differently. The questions guide students to think deeply about the experience, and many have indicated that the open-ended nature of the project makes it the most authentic science experience they have the opportunity to complete while in high school.
This modified version of the Carbonate project is a way to make the open-ended nature of scientific research accessible to the high school student, sparking interest and developing skills.
Preparation:To get ready for the lab I create jars of unknown samples, labeling them A, B and C. Each jar contains about 2-3 grams of the individual sample and is typically enough for students to complete two to three experiments. I pass out unknowns to groups of students as their plans are approved. I make sure that balances, eudiometer tubes, bunsen burners, funnels, filter paper, beakers and deionized water are available. I also try to have a decent quantity of 3M HCl and solid Calcium Chloride at the ready, as they are something students often request. I keep all of these materials easily accessible for me, but not displayed for the students. I want their research to influence their planning more than visible equipment.
