Water Rockets. Either have all the kids (young & old) decorate the rockets together, and then shoot them off as a group. OR, split up older and smaller kids and have the younger kids do a non-water rocket.
Lately my life has revolved around planning my kids’ birthday parties. My daughters are almost exactly two years apart in age, meaning that only nine days separate their birthdays. For me, that means back-to-back birthday parties!! Since the parties are being held on consecutive weekends, I knew I would have to start the planning early if I wanted to get everything accomplished. Enter Pinterest.