Julie Wiener writes about 505 students enrolled in the first and only fully online Jewish day school in the world, The Chabad-Lubavich's Shluchim Online School. Students, ranging from pre-K through ninth grade, log in for as many as five hours of live Judaic studies each weekday, interacting via videoconference, text chat and by “writing” on the electronic classroom’s whiteboard. At any one time, participants can see five classmates and the teacher on their screens.