It seems that classrooms nowadays are all about the computer—we've gone from learning our ABCs to our CD-ROMs in a flash. By contrast, I love the retro-looking book-filled cubbyholes pictured here and the "Guidelines for Readers Workshop" posted on the wall:
1) You must always be reading or writing your thoughts about reading;
2) You need to work silently to enable your peers to their best thinking;
3) Use a soft voice when conferring;
4) Select books you think you will enjoy and abandon books that aren't working for you after you've given them a good chance;
5) Record your reading in your reading log every day;
6) Always do your best work.
Classrom* and Clasroom* are both present nine times in OhioLINK, along with Classrooom* five times. Taken in the aggregate, these typos would be classed as "high probability" on the Ballard list with plenty of room to spare.
("A typical classroom library—probably 3rd grade—at an American elementary school," from Wikimedia Commons.)