read and write time to the nearest hour, half-hour, and quarter-hour;

http://www.numbernut.com/basic/activities/dates_4card_time_nonum.shtml

http://www.oswego.org/ocsd-web/games/StopTheClock/sthecR.html

http://www.oswego.org/ocsd-web/games/StopTheClock/sthec1.html