Olly, Olly, Oxen Free (1978)

Albie and his best friend Chris want to come up with something special to celebrate the birthday of their late-grandfather. Something everyone will remember. When granddad was young he flew through the air in a magnificent balloon using the name "The Great Sandusky." What better way to celebrate his life than to recreate that experience for all the world to see! So Albie and Chris decide to re-inflate the old balloon - but they can't do it alone. It will take all the energy and creativity of their new friend, the eccentric and fesity Miss Pudd (Katharine Hepburn), to help the boys with their adventure - and before she knows it, to share in their adventure too!