I usually divide this activity into 3 parts. The first is to hand out the sheet of images and have the students try to guess the object and either its origin or use or both. They have a lot of fun doing this in pairs. After they have had some time to talk this over, solicit their answers and then hand out the text document. This can be read through as a class or individually. Finally, after reading the examples, they have time to create their own invention. Normally I ask for a name for an invention that would be useful to us today. The main points of the invention could be the title, what it is, how does it work and what does it useful for.