The teacher may use any or all of the following for evaluations:

1.  vocabulary test
2.  draw and label the life cycle of the butterfly
3.  poster evaluation for accuracy
4.  criss-cross puzzle 
5.  puppet construction

Conclusion

Have you solved the mystery? Pilly was not kidnapped after all.  In reality, he underwent a metamorphosis.  Pilly changed from the larva (or caterpillar) stage, to the pupa (or chrysalis stage), and finally to the butterfly (or adult) stage.