1. =Trend() in excel. I SHOULD understand it, but not yet. Right now if I want to predict future numbers based on past, I determine the percent change average and use it to get the next number and the next, and so on. Actually, since I am self taught in Excel, there are a number of formulas I don't understand. And some of those I use on a regular basis because I may not know why they do what they do, but I know they get the answer I need (cause I use formulas from other people's files).
2. Economics. I don't understand how the government can be trillions of dollars in debt and still pay for other people's debt. E has explained this to me several times and I still don't understand it.
3. Mean people. I don't get how people can insult each other just cause they think something different (ie politics or parenting style), or how people can intentionally be hurtful to others (bullies, especially the adult kind who most definitely know better).
4. I'll never understand people who break the law. I'm thinking criminals here, but I struggle with the concept of law breaking entirely. E points out that if no one broke the law in Germany, many Jews would not have survived, or if people didn't break the law in the civil rights movement, there would not have been integration or President Obama.
5. I don't understand how babies learn. I've taken the classes, read the books, and still find it something of a mystery how a baby learns to talk or later learns right from wrong.