This week’s Pre-Algebra Problem of the Week, “Happy New Year Wish,” was so much fun! It’s based on the true wondering that our colleague Suzanne had when she wished her son, Specialist Lee Alejandre, “Happy New Year!” while he was stationed in Seoul, South Korea. She wondered why the time was 14 hours earlier in Seoul, and what it had to do with the longitudes of Philadelphia and Seoul.

I had so much fun reading students’ work as they connected their understanding of math to their thoughts about time zones, globes, and longitudes. There were many different solution methods, and students talked a lot about how they got started on the problem… whether it was talking to friends, getting out a globe, drawing a picture, Googling, or thinking of a simpler related problem. Here are some of my favorite quotes! I wonder if this problem was extra “juicy” because it was about a real puzzle…

Student eleven from Caughlin Ranch ES brought up an important point: what happens if we thought about going east from Seoul to Philadelphia, or west from Philadelphia to Seoul? Why can’t we base our calculations on the 157º difference. Here’s what Student eleven had to say, “i also remembered a time when a book was answering a question involving the international dateline. this told me that the same thing would work going west but you’d go +1day. so goin east would be less complicated (i assumed).”

Julia R. from Birch Wathen Lenox School helped me think about how to decide which way to round in this problem when she said, “Although the numbers werent exact, 210 degrees meant that the time was passing through the 14th hour of longitude, and aproaching the 15th. It was closer to the 14th hour though.” Did you think about why, if 203º of difference is 13.53333… hours apart, we round to 14 hours instead of 13? Did looking at a globe help you decide? Read More→