I have the same labeling system for the same type of tables. I simply write
the name of the table (ie red) on a construction paper shape and tape it to
the front of the table. Classes with seating charts have the kids' name
written on the colored paper instead of the word. This way little ones get
word recognition, older learners know their seat and are easily moved around
if need be. Sometimes I change the table relationships to warm-cool instead
of primary -secondary; all I have to do is move the sign. Its easy this
way! :)