Playing Math at the NCTM Regional in Seattle

Christopher DanielsonEvents, We think math is fun!Leave a Comment

We were invited, along with the Seattle Universal Math Museum (SUMM) to host a play space at NCTM’s Regional Conference in Seattle that took place earlier this month. The whole team organized materials, and then Matt Hertel and I met in Seattle ready to play math! Due to the nature of the space, and fire codes and whatnot, we had

Curve Stitching Parabolas

Christopher DanielsonWe think math is fun!Leave a Comment

Two wooden arms with regularly spaced holes are attached at one end with a bolt and wingnut. The arms are at approximately a 90° angle to each other. Threads are methodically stitched through the holes: the first hole on one arm to the last hole on the other, then the second-to-last hole to the second hole, etc.

Does this method of curve stitching make a parabola, or just something that looks kind of parabola-ish? Geometrically, a parabola is the set of points in the plane that are equidistant from a point (the focus) and a line (the directrix). The parabola whose focus is the point (0,1), and whose directrix is y= -1 is algebraically defined as y=¼

Curry Triangle Paradox

Christopher DanielsonWe think math is fun!Leave a Comment

Five parts for a curry triangle lie slightly separated in order to make clear the decomposition. There is a 4-by- right triangle, a 9-by-7 right triangle, a 4-by-3 rectangle, a figure made of rows of 4, 3, and 2, and another of rows 1, 2, and 3.

Here’s the rap. Me: Can we do a little math together? You: Sure! Me: Here’s a triangle, right? You: Yes. Me: OK. You hold these pieces; I’m gonna swap these, and your job is to fill in the empty space to make the same triangle a different way. … Eventually (anywhere from 10 seconds to 2 minutes later) Us: Oh