My lesson idea is an investigation into how old technologies worked. Piggybacking off the phone example from the lesson. The students could be presented with a series of phones over time starting with the early operator phones to rotary phones to touch tone phones. They will play with them and come up with ideas how they worked. They can be challenged with questions, for example, if they work out that on a rotary phone they have to turn the number to a certain point then ask, but how does the phone know what numbers you have pressed? same thing with the touch tone. This will culminate in an attempt to demonstrate how these phones worked n front of the class by confident volunteers.