The single most important award that your son can earn every year is his rank badge:

All scouts:  Bobcat Badge in their first year of scouting

1st Grade:  Tiger Badge

2nd Grade:  Wolf Badge

3rd Grade:  Bear Badge

4th Grade:  Webelos Badge

5th Grade:  Arrow of Light

Unlike many other youth organizations, your son will not be awarded this badge unless he has completed the requirements to the den leader's satisfaction.  Your son should work in conjunction with his den leader & his parents to get the work in the handbook completed prior to the end of the school year.