Okay, not all of us love looking at real spiders. But this cartoon video does a great job of showing how a spider builds a web, and with just a cute drawing as the spider. It’s amazing to see how they build. If you’ve ever seen a real web, it has bigger and bigger rings stretched across spokes that stick out from the center, like a bicycle wheel. It turns out the spider first has to stretch the edge pieces; then it runs a thread from the middle of each edge to the center, dividing each section into triangles. Since spiders can’t fly, they have to walk to each spot, attach the silk, then walk to the next spot…no wonder they’re hungry when they’re done!
Wee ones: If a spider makes a shape with 4 threads around the edge, what shape could that be?
Little kids: If a spider makes a triangle, then runs a thread from each corner to the center, how many threads did the spider make in total? (You can count them as separate pieces, even though it’s probably all one long silk.) Bonus: If the spider now connects the middle of each edge to the center also, how many new little triangles has the spider made?
Big kids: If the spider connects the tips of 2 9-inch long branches, it has to walk up the 9-inch stick, connect the thread, walk back down, then walk up the other 9-inch stick. How far has the spider walked? Bonus: If a spider’s web has 48 inches of thread, and the spider had to walk double that distance to make it, how far did the spider walk in total?
The sky’s the limit: If a spider makes a ring divided into 20 triangles, how many pieces of thread does the web have? (Hint if needed: Each place a triangle touches the next, their 2 sides share just 1 thread.)
Answers:
Wee ones: Lots of choices: a square, rectangle, diamond/rhombus, trapezoid, or parallelogram!
Little kids: 6 threads: 3 around the edge, then 3 more from each of the 3 corners. Bonus: 6 little ones — each of the first 3 triangles gets cut in half to make 2.
Big kids: 27 inches, since it has walked the 9 inches 3 times. Bonus: 96 inches of walking.
The sky’s the limit: 40 threads. There are 20 around the edge, then 20 running from edge to center.
