Help your class get to grips with using the Nth term via this fun PowerPoint resource for your IWB.
A square is removed from the board each time students answer a question correctly, gradually revealing an image taken from a popular film.
First, print off all the questions and get the students to answer as many as they can in their books. Then, as a class, have the students volunteer their answers. If a student volunteers the correct answer, click the relevant box to make it disappear and reveal part of the film still.
(You might want to ask students to wait until all is revealed before actually identifying the film, so as not to spoil things for everyone else.)