You have a kid. You buy them a toy, it's got the blocks and the shapes. You're young and just getting started at your new job so it's a cheap toy. The plastic bends and your kid can put that square peg through that round hole. He does this over and over and because it works, you never correct him. A few years later you have another kid. You've made more money at your job so you buy your second kid a fancy wooden toy with the blocks and the shapes. Your first kid comes along and does what older kids do and plays with their sibling's toys. Your older toddler picks up the square peg again and smirks, he knows exactly what to do. Except, oh no, that square peg quit fitting into the round hole. If they were a bit wiser and more observant, they'd see the materials of the toy changed and now things don't work as they did before but they never caught onto this because the flimsy plastic toy from before never failed them. Eventually they get tired of the square peg no longer fitting and they throw the toy down and walk away angry and, sadly, not any wiser.
