Switching it Up: Do the Lab BEFORE the lesson!
When you think about how scientists conduct investigations and learn new things in science they often do so through carefully planned laboratory experiments. So why do we teach the lesson before the lab, then expect (consciously or not) our students to find the "right" results? In this post I explain how I choose to do the lab before the lesson at strategic points in different branches of science to help students experience the scientific process in a more authentic way and build investigation skills at the same time.
Flipping the Lab in Chemistry: Percent Yield
The first Chemistry unit in my 10th grade Integrated Science course is about Stoichiometry, we begin with percent composition, the mole, molar mass and end with limiting & excess reactants. The second lab of the unit is one in which students react calcium carbonate with hydrochloric acid to produce carbon dioxide (download it for free below) and then use their knowledge of mass-mass equations to determine the percent yield of the reaction. At this point students have learned about mass-mass equations, but have yet to learn about percent yield, what is is or how to calculate it.
Rather than teaching the Percent Yield lesson first and then doing the lab, I do the lab first so that when I teach the lesson students have a recent chemical reaction which they can use to help them understand the concept. We can discuss common sources of error or things which would reduce yield in this particular reaction, such as the loss of calcium carbonate when students pour it into the Erlenmeyer flask or the importance of taring the balance correctly to ensure accurate measurements. I have noticed that my students understand percent yield much more easily when I do the lab first and they approach the lab without looking for the "right" answer, but simply to follow the procedure and see what they find.
Flipping the lab in Biology: Heart Rate & Homeostasis
In this same Grade 10 Integrated Science course I begin the year with my unit on Systems & Homeostasis, it is an interesting and particularly relevant unit and one which students are able to contextualize very easily. After only two lessons of the unit we begin to prepare for the Heart Rate & Homeostasis lab, during which students will investigate how an independent variable of their choice affects the heart rate of a large sample of individuals. They have learned about homeostasis and feedback loops, but have yet to learn about the circulatory system, which comes near the end of the unit. This means that students only have their prior knowledge and personal experiences as well as their understanding of homeostasis to help them make predictions about their investigation.
Students can choose any independent variable they like and must plan their own methodology to complete their data collection. We discuss consent forms, how to use a blood pressure cuff or other heart rate monitors and the importance of constants & sample size before they begin. By placing this lab so early in the unit I am able to ensure that students' predictions are based only on their own prior knowledge and not informed by our lessons. This also prevents students from looking for the "right" answer in their data... an easy thing for students to focus on when they know what to expect. Once we get to our lessons on the circulatory, endocrine & nervous systems we use this lab as an example, which is all the more powerful because the students have spent time working on it themselves. They watched participants do jumping jacks or take deep breaths or some such task and measured their heart rate. I have noticed a huge difference in student understanding and development of investigation skills once I started flipping this lab.
Flipping the lab in Earth Science: Ice Core Analysis
Climate change is a very important topic for our students to understand, yet much of the evidence is found in huge data tables or on large graphs and can feel unapproachable to students. One way in which I help my students better conceptualize the evidence we use to better understand climate change is through an ice core analysis lab. By making homemade ice cores in plastic graduated cylinders students are able to analyze the pH (for carbon dioxide levels), sediment and volume of each year's ice. I use food colouring to help make the layers easy to see and then students dissect and melt each layer to analyze them (see free lab below).
After we have completed this lab students then learn about secondary data for climate change (or proxy data) such as ice cores which allow us to analyze trends which are more than a few hundred years old. Once again, by flipping the lab and doing it first students go in without a preconceived expectation of what the "right" results are and they then have a familiarity with ice cores when we talk about them in the lesson. It works really well!
Preparing Students for IB & AP Sciences
Developing investigation skills and scientific literacy is an important part of any Science program, but it is even more crucial when preparing students for particularly content-heavy advanced science courses such as AP or IB Diploma Sciences, both of which I have taught. In my experience students are so focused on the large amount of content in these courses that they don't have time to develop investigation skills from scratch and a solid foundation is critical to their success. A simple way to prepare your students is to flip the lab and have them draw conclusions from their investigations BEFORE they learn what science has to say the answer should be.
The beauty of this strategy is that it is a low prep and easy way for teachers to build investigation skills, keep the labs you know and love.... just include them earlier and refer back to them in your lessons.
Thanks for reading teachers, travelers & curious souls of all kinds.
The Roaming Scientist
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