. - t> ~ . o 4 <l 0 • - <l 0 • • 6 .. 0 How often do you fall a leep in clas during a week's time? .. 0 • .. 0 a. three time a week 45 01 .. [). • [). b. two times a week 20 0 - o ~ c. none 35 5' • o ~