I have frogs in my room and we always grow one. We have a tank with 3 frogs in it and then we grow another during the life cycle part of my science unit. they love it and we "pick " one person to take the grown one home. I never announce that until i know it is going to grown and be healthy. I mentioned it one year and it never developed so it was quite traumatic.
Enjoy and be prepared to have the all things dont work out discussion.
The k classes at my school raise chicks from eggs and that is A LOT more responsibility than a frog, so I'm sur eyou will be fine and most importantly, enjoy!!!