For a second year in a row, I did gravity boats with my class.
We used Science Max as our model again
This year saw the boats improve in leaps and bonds. There were only 3 boats that did not post a time. Two of those were only focusing on how their boat looked. One didn’t even have a cup on it. We also had about a 2/3 finish rate (if you exclude the 2 for looks boats.) This was a huge improvement on last years 80% DNF rate.
The times this year were also significantly faster. Last years stats were:
The fastest boat made it in 5.38 seconds
The slowest made it in 20.89 seconds
The most consistent boat was within 1.5 seconds between its three runs
This year, the fastest boat was 2.97 seconds. Of the times that finished, only 4 were slower than last years fastest boat. One of those was the slowest at 12.78 seconds. The most consistent boat had 3 times within .1 seconds of each other. Overall it was an impressive improvement across the board.
There were 2 big changes that the class figured out through experimentation. The first was that a wider boat is better. With the exception of one boat, all of the fastest boats were about 20 cm wide. We think the biggest reason this worked, was that it made the boats less likely to tip and allowed the boat to hold more water. The second innovation was to cut up the straws provided and have multiple exit points for the water. The winning boat had 8 straw pieces letting the water out. The combination of these 2 things led to a huge improvement of speed.
The other trend this year was to try having 2 cups running at one time. No one could get this to work consistently. The first problem was getting both cups filled equally at the same time. The second problem was getting equal amounts of water out at the same time. This seemed to cause the boats to turn significantly, especially if one cup ran out sooner than the other.
Overall, it was another great success, with tons of engagement, awesome ideas and experimentation, and of course, a giant mess.