6.4.1, "binomial" distribution

[michaeladamkatz]

I happen to know from prior classes that the "binomial distribution" is so called because of the coefficients you get when multiplying out (a + b)^n. It feels to me that it would be worth saying this (and maybe giving the example of (a + b)^4 to show how the coefficients work out), because the term "binomial" just sounds so mysterious otherwise (you ask yourself: "two numbers? what two numbers?"). Given the choice between saying something about (a + b)^n vs. dumping the factorial formula, I would choose the former (but of course you can do both).