Prof Oja-Aha at the movies

This is probably the 9th season I'm drawing the comic 'prof Oja-Aha' for childrens magazine Taptoe. This episode explains what kind of tricks are used in movies. It's page 1 of 2, so be sure to buy a Taptoe to see how it ends... (I'm kidding, it's not for sale, you 'd have to be in a dutch school to get it.