I'm going to go over the numbers and show them whatever different types of money I happen to have on me. Luckily enough this includes won, dollars, euros, pounds and the clincher - 100trillion pound note from Zimbabwe!
Gonna do the price is right with them as well. It seems a good one.
Also, I'm thinking of handing out fake money to the students for answering questions, good behaviour etc., redeemable at the end for jellies or sweets or something.