Last month, SciAm.com ran a story about how bad weather can change the length of a day. Well, if you had any doubts, it turns out that high temperatures can really affect how a wristwatch keeps time. That's what we learned when we stopped by Andrea Carter's booth here at the Intel International Science and Engineering Fair. Andrea, a student at Noblesville High School in Indiana, took six quartz crystal-based wristwatches and kept them at six different temperatures, ranging from -8 degrees Celsius to 58 degrees Celsius. (She used an Easy Bake Oven-like setup in one case.) After she did a sophisticated statistical analysis, she found that the watch kept in the warmest temperature lost seventy seconds in a week, compared to standard GPS time. Cold didn't have much of an effect, and the watches kept at near body temperature kept good time, which makes sense because that's the point around which manufacturers calibrate quartz crystals. If she continues on the project, she'd want to look at the effects of humidity. This isn't exactly what Intel Science Talent Search finalist Keith Winstein " whom we profiled today as part of our Where Are They Now series -- had in mind when he wrote about government efforts to get rid of "leap seconds."� But it could help you know when your watch is keeping good time.