Last week I gave a new type of lesson a try where I use groupwork and problem solving to introduce content to students. It wasn't as successful as I had hoped, so this week I tried again with some changes. I structured this lesson on the Launch, Explore, Summarize method.
To start the morning off I gave everyone a card at the door with numbers and letters on it. This was my quick randomizer and I had them sit with their number or letter pairs. Once they were sitting I showed them a marble and a tennis ball that I had. We weighed them, and finding that the tennis ball was 10x the weight of the marble I asked the groups, "If these were dropped at the same time, which one would hit the ground first?". After they had table discussions I led a class discussion, probing and asking questions. Then I climbed up a ladder and dropped the marble and tennis ball together a few times for them to see. I asked if there was a difference in how hard the two balls hit the ground. This led into our question for the day - "How can two things move at the same speed but hit the ground with different strengths?"
Here I gave every group a ramp, block, legos, a tennis ball and a marble. With these I shoed quickly how we could quantify the strength each ball had by putting the wood block at the bottom of the ramp to be pushed by a ball after it had rolled down the slope. I gave everyone the instructions for the mild, medium and spicy tasks and put a timer up on the board for 25 minutes. I'll describe the tasks below.
- Mild Task - "Measure how strongly each item hits the block at different heights of the ramp. What’s the strongest collision you can make? What’s the softest collision you can make? How many collisions can you make that are in between?" For my low floor task I wanted to see groups just measure different forces and connect them with masses and accelerations
-Medium Task - "Measure how fast each ball moves down the ramp at different heights and how hard each hits the block. What’s the greatest speed you can produce? What’s the slowest speed? How big or small of a collision can you make with each ball? Speed = distance/time" For this task I pressed groups to make specific measurements and calculations related to the physics at work. These were accessible as straight forward division and many students chose this option.
-Spicy Task- "Measure the acceleration of each ball at different heights of ramps. Use this to calculate the force of each. Acceleration = distance/second² Force = mass x acceleration." This task was the most complex and led to some great discussions with those who took it on. Going one step beyond just speed to finding acceleration and then calculating the force of each collision in Newtons proved a task that many of my students enjoyed.
At the end of the 25 minutes of working time I had everyone finish what they were working on and have a discussion about our main question now that they had done some research. I asked them to use their findings as evidence. After letting them talk for 5 minutes as table groups I led a discussion on our main question. I asked for details and examples from students experiments. To finalize I showed the equation for Force on the board behind me and we talked about some examples.
This was a much more successful and engaging lesson that last week, both because the students had objects to manipulate and test, and because I kept an essential question in focus for the whole lesson. To promote positive group work I randomized the partnerships. I felt comfortable making these randomly because of the short duration, and the quality of work was higher than in the past. In the future I would use another method of sharing out to help everyone have a voice, such as stickie notes or posters to remove any barriers people might feel around sharing.
Philip Estrada is a teacher at High Tech High Media Arts in San Diego California. He teaches Physics by having kids build things in a woodshop.