Students love heat sensitive pencils from U.S. School Supply. These thermo pencils change color when you rub them with your fingers. We offer these heat sensitive pencils in several different designs that are sure to please your students and will make a great addition to the school store.* Click Product Picture for Larger Image and More Product Detail!e offer these heat sensitive pencils in several different designs that are sure to please your students and will make a great addition to the school store.