Sargent Art-Time Tempera is a good choice for your classroom (or dining room / craft table).
Vibrant colors come in various sized jugs. Parents and teachers can clean messy hands and brushes with soap and water.
Art-Time is the new name for Gothic - but with the same quality you would expect from Sargent., ample coverage and true mixable colors. Sargent Tempera is non-toxic and proudly made in the USA.