Great question.
So first off, Congrats on getting your team ready to punt in 4th grade!
You can definitely do it if you want and it is a live ball and can be downed anywhere.
The rule everyone is probably getting confused about is when you do the punt declare. If you choose this option, it will never be downed inside the 20 yard line.
Here is the rule:
20/20 Punt: Teams may elect to attempt the punt.
However, they may also opt to declare the punt and the ball will advance 20 yards down field.
The Ball will never be placed inside the opposing team’s 20 yard line. (rule should add - on the punt declare only)
Did we end up getting it right?
If the answer is no, Please let me know where you were at I can inform the officials of the rule.