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What’s the Problem?: Hourglasses

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A la Dan Meyer‘s Three-Act Tasks, I’d like to try a few science-related ones. I think a lot of Mr. Meyer’s scenarios could be science-y, but in the context of math class, they’re math-y. Actually, his method for creating the Task is pretty close to Scientific Method, i.e., observe a Thing, wonder, test. Booya! science for the WIN!


Maybe this is just a version of discrepant events. This particular one isn’t terribly discrepant, but maybe it’s a little strange. Here’s the first (I hope) of a series I’m going to call, “What’s the Problem?”

Act 1: Observations and Hook

There are a lot of possible questions here. It’s almost toward a 101qs-type thing instead of a particular task.

Act 2: Questions, Possibilities, Resources

  1. List all of the parts seen in the video. List other characteristics of the hourglasses.
  2. Why so many hourglasses?
  3. How long do they run?
  4. Are they supposed to be the same time length?
  5. Is the one with the most sand the longest?
  6. Does the sand fall at the same rate for each hourglass?
  • Hourglasses each have a clear barrel, black end-caps, and some amount of sand. Characteristics that might differ include the width of the barrel, the width of the narrow opening between top and bottom.
  • There’s a board game that came with these ten hourglasses.
  • They vary in timing-duration from 25 seconds to 1:07 minutes, according to my stopwatch.
  • They are all supposed to be one minute timers.
  • The one with the most sand is not the longest timer-length (it runs about 1 minute) The one with the least amount of sand, however, is the shortest.
  • Sand does not appear to fall at the same rate (the shortest duration hourglass appears to pile up more quickly than the rest).

Act 3: Resolution and Continuation

In order, the duration of the hourglasses looks something like this:

hourglasses in order of duration

0:25, 0:50, 1:00 (x3), 1:01, 1:02, 1:04 (x2), 1:07
Note: that the amount of sand does not appear to increase consistently as duration increases

  • Only three of the ten hourglasses actually run for one minute (although two others run 1:01 and 1:02).
  • How might this potentially affect game play for the board game?
  • Why doesn’t the amount of sand seem to matter for duration (i.e., other factors in falling sand)?
  • Could we make them all into the one-minute timers with current materials?
  • If we could open all of the timers and make them equal duration, what would that time be?
  • How might these hourglasses have been made in the first place, since they are not terribly accurate?
  • Would weighing them help?
  • How would a different grit of sand help or hurt?
  • Would a different color of sand help the stopwatch-holder (and board-game-player) see the endpoints better?

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