Jane has $3.05 in nickels and quarters. If she has 13 more nickels than quarters, how many coins does she have? According to the conventional thinking, real-world examples such as this one are the best way to teach mathematics. When researchers at Ohio State University tested this hypothesis, however, they found the opposite to be true. They showed college students a mathematical pattern using either a concrete example (in this case, measuring cups filled with water) or an abstract example involving symbols, then had them play a game that drew on their new skills. The subjects who saw the abstract example performed significantly better in the game than did those who learned the pattern with measuring cups. Jennifer Kaminski, lead author of the study, hypothesizes that real-world examples might distract students from the mathematics being represented. “We think what’s driving this is attentional focus,” she says. (And by the way, Jane has 29 coins.)