This summer I was asked to provide some programming for the oxford Literacy Network. This is a great organization that provides summer activities for kids in our community. They host programs in three different sites around the area for kids K-5. They program for 2 weeks in the summer, serving breakfast, helping kids select books at their reading level each day, and providing some sort of interactive program each day. For a couple of those days I was that programming. I wanted something the kids could make and take with them, learn a little about STEAM, and learn a couple new words. I decided to go back to a tried and true friend, the hand helicopter. These are fairly quick, easy, and inexpensive to make as well as being customizable. When we were preparing to make these with kids at Cincinnati Mini Maker Faire a couple years ago we invested in a number of lunch trays and laminated templates kids could use as guides for all the parts they needed to cut.
The trays are great for gathering and keeping track of supplies. We tape the templates to the trays and set up little assembly lines of supplies. Due to the young age of the children and the short time window I decided it would be best if I manned the hot glue guns for the day. The kids could measure and cut all of their parts and then personalize them while waiting for my rapid-fire glueing.
It is easy for me to take pictures before and after activities but it is a challenge when I have a line of kids wanting hot glue to pause and take pictures, so you will have to imagine that part of the day.
Our two words for the day that we learned together were CONVEX and CONCAVE. When we make the hand helicopters the propellers are made from large craft sticks, otherwise known as tongue depressors. These light pieces of wood almost always have a natural curvature to them. I explained the Bernoulli principle in the most painless way possible with a quick illustration on my portable whiteboard. I drew a basic cross-section of a wing - flat on the bottom, curved on the top- with arrows indicating airflow. I explained that the air that is split by the wing has to meet up at the back side of the wing at the same time. Given that the air traveling over the top curved part of the wing has to travel further it must travel faster. That faster speed results in lower pressure. The slower travel across the bottom provides higher pressure. We at MAKETANK remember this as, "High velocity, low pressure is my gift. Low velocity, high pressure gives me lift". It makes sense to us.
So, as the kids select their craft sticks to be their propellers they want to determine which side of the stick is convex - domed like the top of the wing- versus concave - scooped out like a cave. This way they can be sure to have the convex side on the top side of their helicopter and achieve greater lift with their toy. The kids seemed to get the idea, learn their words, and enjoyed making the copters. I did this project one day a week at different locations and each day was nice enough that we could go outside and give them a whirl!