This is now the fourth in a series of posts featuring St. Gregory classes which exemplify (imho) the type of teaching and learning Tony Wagner calls for in his book, The Global Achievement Gap. In that book, he asks for schools to uses academic core subjects to teach students to reason, communicate, and solve problems; here we present a Chemistry class that does exactly that. Dr. Wagner will be here at St. Gregory in just a few days, and on the day he arrives we will present him and publish our new booklet: Bridging the Gap: Teaching Students to Communicate, Reason, and Solve Problems.
This is from Dr. Scott Morris, our Science Department chair.
Students know they will be doing a lab today. Their homework assignment was to download the procedure from the teacher’s website, read it, and prepare any data table(s) that they think will be useful.
The teacher begins by asking whether everyone has a copy of the procedure and then queries them along two lines: What are we doing and are there any hazards we should be aware of? They will have to write a lab report after the activity, so he asks them: “What is the purpose of this lab?” The students volunteer opinions and the class develops both a “scientific” purpose as well as a “technique” purpose. Often, the “hazard” discussion is blended into the pedagogical goals:
1) Are we using fire? Why?
2) What is the potential for explosion? Why?
3) Why use a hot plate rather than a lab burner?
4) Are any of the chemicals hazardous? (They already have learned how to interpret the chemical labeling system.)
5) Why should we heat certain substances only under the fume hood?
6) Will we need goggles? Why?
After taking any final questions about the procedure, the teacher sends the students over to the lab area. Sometimes they can choose lab partners; sometimes they are assigned to groups. Rarely are the groups bigger than three students. The teacher provides some helpful hints as the groups get everything ready. He reminds them that there are often different ways to do the experiment; however, they must have their experimental setup approved before they begin.
As the students work they ask questions, which the teacher directs back at them or to other members of the group.
1) Why do we leave the lid on the crucible? (What reasons can you think of?)
2) Why can’t you touch the crucible after the first heating even when it has cooled? (What might affect the mass measurements?)
3) Is this a chemical change? (Any evolution of heat and light? Unexpected color change? Production of gas? Formation of a solid precipitate?)
4) Can we light this on fire? (What does it mean to “burn?”)
5) Why does it change color from green to yellow? (What causes color?)
6) Can I dispose of this in the sink? (What is in there?)
After the groups finish and clean up, it is time for debriefing. The teacher brings up the posted report guidelines on the Smartboard and the class concentrates on the hypothesis, observations, and logic behind the calculation requirements. Students often want to make the hypothesis about the experiment, so the teacher reminds them that it is really the other way around: what is the Big Idea they are testing? The merging of the chemistry concepts with math skills is often challenging, and so the class spends the rest of the period organizing the raw data and finishing their calculations. At the end of class, the teacher announces the deadline for the submission of the written reports.
Often on such lab days, a slight deviation from the procedure results in an unexpected outcome (different color, failed reaction?) which extends learning beyond the immediate purpose of the experiment. Other labs require that students design a method to accomplish an experimental goal (suspend a piece of magnesium at some height in an inverted tube of acid, contain a gas in a chemical reaction, remove a solid from an aqueous solution, etc.) and they are invariably asked afterward to evaluate their design and suggest improvements.
In total, these classroom activities stimulate curiosity about the natural world, foster critical thinking and collaboration about what was observed, and hone oral communication skills by discussing outcomes. They also encourage initiative and adaptability in assembling lab equipment to accomplish experimental goals.