I call students to the gathering area and I announce that today we start to build! After the cheering has died down, we get down to the nitty, gritty. I tell them that any good engineering or construction project has a budget. Each group will have a budget of 35 sheets of cardstock, one roll of scotch tape, a tape dispenser, and a roll of masking tape (not to use, but as a form for loops). The final constraint is that students must build on a 60cm X 60cm base. I provide the poster board pre-cut to size.
I tell students that the best way to use their card stock is to cut it into thirds (depending on the class, I might do this on the paper cutter prior to the class. Other classes, I let students choose how much they want cut and how much they want to keep). I cut any paper for students as I can use the paper cutter and keep edges straight and precise, which is imperative for good structural support.
I tell students that this is an independent project, but I will be at the table for any tutorials necessary to help students move forward.
Before letting students begin, I provide some support for making components. This reduces the amount of paper loss incurred by groups.
I demonstrate how to make a:
I provide step-by-step handouts for these for future reference, and I also have a set of videos linked on my class website for those who need a visual or my ELL students who need sheltered instruction. I complete about three of the different components while students observe, but this is all I need to do. The basic curves and corners are just repeated for different components. Students do not want to be shown them all, but instead begin to experiment themselves, even while I am demonstrating. No video tutorials needed. Students are much more attuned to this than I expected.
I also hand students a tip sheet with helpful hints like, build from the bottom! Yes, it is surprising how many students forget this very important component. This is where a well-designed coaster sketch is very helpful and students have to think backwards in order to build the roller coaster.
I find that this project takes about 8-10, 45-minute sessions. My students have to move their roller coasters at the end of each session so my room is not overrun, so it is super-important to provide a sturdy base or previous work becomes undone.
Students build their roller coasters as they have sketched them. They may use all their materials or less, but they cannot use more. If they have to rebuild a section, I suggest they recycle their materials as much as possible, but this is a lesson in precision and perseverance, as well as, science.
As students build, I move around the room, or I provide tutorials for different aspects of the build. Often times, I see students tear down and re-build. This is a great example of the “Improve” stage of the engineering cycle. It is also great evidence of learning occurring as students try and fail and figure out the mechanics of the energy needed to make the marble run.
Students will be assessed for the time the marble remains in motion as well as evidence of an energy transfer of some sort, somewhere in the run. Energy transfer is not the same as energy conversion, from potential to kinetic. Energy conversion must transfer energy from the marble to move an object such as a door in the track, start a windmill turning, transfer energy from one marble to another (this marble must be placed in the track prior to starting the first marble, or transfer energy at the bottom of the coaster).
Students should be given at least a full week to build before assessment.