As a class, build the island out of paper mache onto a large table. Talk about what resources the Robinsons would have on an island to build shelter, grow food and so forth. Assign small groups projects to add to the island, such as the tree house, the cave, animals, vegetation and other things of interest on the island that help to tell the story. If possible, take the class for a walk to collect twigs and other natural vegetation to build up the island. Talk to the students about how it would be to live on an island as the Robinson family had to do.
Ask the students to brainstorm and list the various inventions that were made by the Robinson family within the story. Challenge the students to try to think of an invention that they could have made using the resources that the Robinson family had. Ask them to identify the need for the invention and what materials they would use to build it and what it does. You can add a really fun twist to this activity by asking them to build and demonstrate their inventions, rather than just writing or talking about it.
Ask the students what types of entertainment the children on the island had. Using the resources available on the island, ask students to make up a game that the family could play. For example, what items could they use to play baseball and how would they play the game. The idea is to have the children make up a board game, a word game, races or any other sort of game or entertainment they can, provided they use the resources available on an island. They must give their game a name, write down the rules and be able to teach the class how to play it. Set aside time for each child to lead the class in playing the game that he invented.
Ask the students to add a dimension to the story by imagining that Franz sees something floating toward the island. It can be a raft with an animal on it, or a trunk drifting in their way. They are to describe what it is that floats their way, and specifically how it changes life for the Robinson family. Explain that this is fiction so anything goes -- perhaps they find a bag of potato seeds that they plant, and end up using the juice from the potatoes for fuel to run a steam engine. Give the students the opportunity to role play the scene when the discovery is made and how it changed everything.