In this sixth/seventh grade science studio, our theme for the year is exploring the variety of practices within the scientific method.
In the first block, we are taking a two-pronged approach.
We’ve spent the first three days thinking about chemical safety in preparation for performing chemical labs later this block. Since our lab is a shared space that lacks the usual amenities (fume hoods, sinks, …) it’s especially important that students have a deep understanding of chemical safety practices, not just memorizing rules but knowing what the rules are supposed to accomplish, so they can adapt intelligently to our particular space. In the general spirit of our principle that Proofniks look out for each other, I want students to be looking out for each other during experiments, and also looking out for the homework lab and math classes that use the space afterwards by making sure we leave it clean.
So far, students have designed experiments to test the reactivity or toxicity of a material. They’ve noticed that the latter, especially, is a hard problem, partly because they don’t know enough facts, but also because ethical considerations prevent the experiments that would be most useful. I want them to start getting a nuanced sense of what we know and don’t know about chemical toxicity, and the complexity of the problem including different types of exposures and different types of harm. For now, we’ll use these discussions to inform our decisions about the chemical safety practices we use in the lab, and we’ll return to quantifying risks in Block 5.
Once we’re ready to do experiments, we’ll switch to the main focus of Block 1, which is basic tools used in the quantitative physical sciences. We’ll study dimensional analysis, a powerful tool for thinking insightfully and calculating reliably that will serve students well in later science and engineering work. Students will perform classic chemical experiments, investigate the importance of random and systematic errors, and find ways to improve the procedures. By the end of the block, they should be comfortable using and converting metric units, estimating quantities by breaking them into pieces and using dimensions, and estimating error ranges on measured or calculated results.
When I taught chemistry at community colleges, this type of thinking (predicting the effects of experimental errors on results, making judgements about error ranges, etc) was the biggest challenge for students, perhaps because they had little control over experiments and no opportunity to repeat or modify labs to test hypotheses about the procedure itself. At Proof School, our investigations will start with students learning a technique by following a standard procedure. After analyzing the results, they will design and conduct a follow-up experiment based on their analysis. For example, if a student thinks that a result depends on the amount of compound used, he can test that hypothesis. Another student might modify a procedure to reduce a source of error she identified. In some cases, we might conduct several cycles of follow-up experiments. Basic physical chemistry provides a relatively simple sandbox for students to engage with experimental design, gain confidence, and experience real experiments, which, unlike optimized teaching labs, only sometimes work as intended.
-- Emily Eames