A biometric bracelet named ''Q Sensor'' is shown in this undated image released to Reuters on June 13, 2012. According to the manufacturer's website, the sensor measures ''emotional arousal in real-world.'' The Bill & Melinda Gates Foundation, which has poured more than $4 billion into efforts to transform public education in the U.S., is pushing to develop an ''engagement pedometer.'' Biometric devices wrapped around the wrists of students would identify which classroom moments excite and interest them -- and which fall flat. The foundation has given $1.4 million in grants to several university researchers to begin testing the devices in middle-school classrooms this fall. REUTERS/Affectiva/Handout
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