MIDDLETOWN SPRINGS — Forget coloring books. Students have switched from picture books to Netbooks, from writing with pen and paper to drawing their own screensavers. On Tuesday, students in grades 4-6 got a primer on how to learn differently in the classroom, by way of laptops so small you can hold them in your hand. It’s the second phase of a project aimed at getting laptops in the hands of students in 24 Vermont towns, spearheaded by the Vermont Council on Rural Development, e-Vermont and partner Digital Wish, an educational nonprofit organization.