Help the youth serve others with babysitting for the temple! Since Activity Day aged youth are not old enough to do temple work, help them allow others to do temple work.
Here are two ways to do this - with "babysitting coupons" and with a "babysitting sign-up" sheet:
Babysitting Coupons: After visiting the temple grounds and walking around the temple for an Activity Days activity (maybe also have them bring their journals and give them some alone time to write in them, sing songs, and if possible watch a temple movie in the lobby), give each youth the "babysitting coupons" that they can take home with them, fill out and then give to whoever they choose/are comfortable with. If you have a younger group (8 may be too young to offer babysitting) maybe have them team up and pass out the "babysitting coupons" in couples.
** When filling out the time on the sign-up sheet, I recommend putting a time frame. Ex. 4pm-7pm... so the parents know they should plan on being back around 7pm.
I also made sign-ups for Young Women's and Young Men's.
You can get my files for this HERE.