Math
The Pythagoream theorem was the first equation I learned. Dad explained it to me standing in te bay window of his living room. This ration, and that all right triangle behave this way as amazing. Math was beautiful; it just worked. I tried to explain it to my third-grad class, but had forgotten too much of it, and my teacher didn't recognize it to help me out. Later, while renovating that house, he taught me about plumb, level and square, none of which that house was: the walls leaned, the floors sagged.
Dad was an electrical engineer who worked for government contractors, first for the military (he watched Sidewinder missile tests), ending his career working on the International Space Station. He was a Ham radio operator, a model railroader, and learned a bit of programming when personal computers became affordable.
When I was in fifth grade, he brought home a small, cylindrical magnets in a plastic tube. Hours passed while I played with attractive and repellent magnetic forces. The force would make the magnet above in the tube levitate, and the space between the bottom magnets was smaller than the space between the top magnets, because of the combined weight of all of them.
Most of what we did together on visitation weekends wasn't math or science. It was renovating the house (Dad gave me my first hammer; my name is on it), hiking, picking blueberries, canoeing, cross-country skiing, ice skating, building the model railroad. He taught me to make French toast, the only dish I can cook without a recipe, and how to know when pancakes are cooked through.
Unlike Mom, Dad wasn't surprised when I said I wanted to study math. He was proud of my internships with the Naval Air Development Center (sonobuoy simulations) and IBM German (Unix and C programming). He was even proud of my detour into reporting, my bridge into tech writing, and that new web thing. I brought him black and white laster printouts of the main sections of this site as I developed them while he was in the hospital.
The recipe: Chrusciki
In years I feel very with it, my stepmother and I will make these the day after Thanksgiving.
The craft: World's easiest table-top Christmas tree
Cardboard and stickers. What could be easier?