Trivia Vending Machine is a very lovely example of a Raspberry Pi project. See https://www.youtube.com/watch?v=n6gs8NtXPIk The "Untrue Zoo" can be created with LiveCode Open Source (free). See https://www.his.com/~pshapiro/UntrueZooHSHTML5/ and https://www.youtube.com/watch?v=37nfon24_aY Bicycle treehouse elevator can spawn a lot of conversation and thinking -- https://www.youtube.com/watch?v=E5FSWkjFPxs Getting kids to make their own screencasts (using free screencasting tools) is always interesting and useful. See https://www.youtube.com/watch?v=M11WT3H_DqU and https://www.youtube.com/watch?v=EvSxhyJhfM8 Get kids into interactive fiction using Twine (free, open source). https://www.youtube.com/watch?v=8gNKhqDr6pg