Leading with the Lab
When I first started teaching fifteen years ago, I ran my classroom the way my high school chemistry teacher ran hers. I decided to become a teacher when I was eight years old so I paid close attention in school to what my favorite teachers did with us so I could duplicate it when I finally became a teacher. A typical unit would start with notes. We would cover basic definitions and vocabulary that would be used throughout the unit. I would then move on to example problems and have the students complete questions from the review sheet in class so I could see they knew how to solve the problem correctly. I would assign daily or weekly homework to reinforce what we were doing in class and administer 5 point quizzes every couple of days to check for retention of learning. Somewhere in the middle or latter half of the unit we would perform a lab to give a context to what we had been learning and then close the unit with some sort of major assessment, like a test.
This method proved to be effective for a long time. I thought I was a successful teacher because I would see the light bulbs go off for students during the lab. I incorporated more and more lab activities to show students there was a practical reason why they had to balance reactions or memorize Boyle’s law. Lab experiments were the “real-world” uses of the material we were learning because “this is what chemists do.” When I heard students say ‘now I get it’ I felt like a success.
Deep down there was something missing for me, though. Science is a ‘Why?” subject; we observe something in the world around us, ask ‘why did that happen?’, design an experiment to test our hypothesis, then go back and revise our original thinking. I wasn’t getting a lot of kids asking why. I got a lot of ‘Oh!’ and ‘Why did you say that in the beginning?’, but not a single ‘why did it do that?’ If lab is my students’ favorite part of class, why do I wait so long to have them perform labs?
I decided that I am going to lead my units with the labs. When we perform the labs first, students ask “why did that happen?” Now the questions drive the learning! At the end of the lab, each lab group must submit 3 questions to a Google Form that I created. I look through the questions and rearrange the lessons for the next day based on what they want to know. Let me give you a couple of examples:
- For Atomic Theory, we start the unit with a flame test lab. It is a traditional lab in which students move to different stations, insert different ionic salts in a burner flame, observe and record their results. Questions that come from the lab are ‘why did each chemical have a different color?’, ‘what other substances change color in flames?’, ‘Could I perform this lab with any substance?’
- For Solutions, we start by making kool-aid of different concentrations to set up our molarity and molality notes. Students choose how much Kool-Aid mix and how much water they want to make their drink out of. They weigh the mix and use a graduated cylinder to measure their water. Students will ask ‘why did I get a different amount of drink at the end if I used the same amount of water each time?’, ‘could I still measure concentration without measuring the Kool-aid in the beginning?’
- For Thermochemistry, students design and conduct an experiment to determine the specific heat of substance. They are given standard lab equipment and a list of objects to study which include toothpicks, cotton, rocks, glass marbles, various metals, isopropyl alcohol, water, and vegetable oil. A thorough explanation of specific heat is given in the introduction along with links to videos explaining the topic on YouTube. They utilize Google searches to find experiments to model theirs after, conduct their experiments and collect their results. They analyze the results after we complete the lessons on heat transfer and specific heat. Questions that arise are ‘Why are metals the best objects to conduct specific heat experiments on?’and ‘How can you test the specific heat of a liquid when it evaporates easily?’
The labs we use in class are very similar to traditional lab experiments. What has made them more effective is their placement in the learning, how student questions are driving the direction of the lessons, and how students are beginning to see science as exploratory instead of sit-and-get.