In Which I Become Overly Enthusiastic About Geometric Solids
Did you know that there are five geometric polyhedrons with all regular congruent faces? The Tetrahedron (triangular based pyramid), the Hexahedron (Cube), the Octahedron, the Dodecahedron and the Icosahedron. They’re called the “platonic solids.”
upon discovering this fun fact, I said “if these are the platonic solids, then what are the romantic solids?”
Benji face-palmed and sighed “Oh my god. That was a dad joke.”
I have no shame. I’m in love with basic geometry.
I introduced “triangular prism” and “rectangular prism” to my seventh graders. I also introduced that there are other prisms, for instance : pentagonal prisms, irregular hexagonal prisms.
“You have to remember triangular and rectangular prisms because they are very common,” I said. “But you don’t have to remember pentagonal or hexagonal prisms. I just think they’re interesting.”
“Interesting? Interesting?” my students echoed incredulously. The look on their face quite literally said “Lady are you kidding me? You expect me to find the word “pentagonal” interesting?” I think some of them were so incredulous that they though they were translating “interesting” incorrectly.
“Yes!” I said. “Interesting. Right?”
Silence.
Benji said he had to resist braying “NEEERRRRD” for the whole class.
Then we did a hands on activity where the students cut out and folded different geometric solids from templates on paper. I was really excited.
“Ooooh, Peter you have rhombic pyramid!” Peter could have cared less.
“Quella! You have a trapezoidal prism!” Quella, like Peter, did. not. care.
“Oh look. Tim, you have an irregular concave hexagonal prism!” They were enjoying the cutting and folding, not the nerdy teacher trying to teach them.
I’m such a nerd I even get excited about 2-D shapes. Neither my students nor Benji appreciate my enthusiasm for quadrilaterals and how they all relate to each other. Rhombuses/rhombi and squares are technically kites! (two pairs of equal adjacent sides)
And if you want to know why I’m teaching advanced geometric solids to Chinese seventh graders it’s because it’s hard to teach abstract math concepts and I’m running out of other math vocab to teach. And prism is a useful word.
but back to me being a giant nerd. specifically about prisms.
Things about geometric solids that make me impossibly happy:
1) Cylinders are essentially circular prisms. Or infinitely sided-polygonal prisms.
2) Likewise, cones are infinitely sided-polygon based pyramids. Even a 20 sided polygon based pyramid looks remarkable conal.
3) The fact that “ovoid” is a word. It’s not an egg, it’s an ovoid.
4) ANTIPRISMS: discovered through the wikipedia page on prisms, their bases are two congruent and parallel polygons connected by an alternating band of triangles. AND THEY’RE AWESOME. Also their name: antiprism
5) Oblique Prisms vs. Right Prisms: I’d never thought of this before but while a right prism has the two base polygons aligned directly above each other (and thus connected with rectangles) the oblique prism bases are still parallel but off set, meaning that their connecting sides are parallelograms. Why does this make me happy? I’m not sure...but I had to resist teach my 7th graders about the dual use of the word oblique as it applies one’s abdominal muscles.
