Hidamari Sketch, Kyoukan Astro Recommendations
Both are four-panel mangas with about the same wacky brand of humor. Hidamari Sketch is about four high school girls going through the same art school together, and is fairly slow paced. S. S. ASTRO is about four young teachers enduring the plights of being a high school teacher, with lots of humor and little bits of romance thrown in here and there. If you like S.S. ASTRO, then I can almost guarantee you'll like Hidamari Sketch, and vice versa.