( Then ( , ( ( ( divide ( your class ) ) ( into ( seven groups ) ) ) . ) ) )
(ROOT (S (ADVP (RB Then)) (, ,) (VP (VBP divide) (NP (PRP$ your) (NN class)) (PP (IN into) (NP (CD seven) (NNS groups)))) (. .)))
Then, divide your class into seven groups.
(ROOT (S (NP (NNS Mollusks)) (VP (MD can) (VP (VB be) (VP (VBN divided) (PP (IN into) (NP (CD seven) (NNS classes)))))) (. .)))
Mollusks can be divided into seven classes.