Warren Buffett has a trick for getting his money's worth out of the stock market, and he says it's a skill "you can learn in the fourth grade" — even though it's "not taught in schools."

At Berkshire Hathaway's annual shareholders meeting on Saturday, Buffett recommended against obsessing over finding a perfect time to buy a stock. Rather, the Berkshire Hathaway CEO said, go ahead and invest, and then observe the stock market over time to see if you should buy more of that company's stock or sell it.