Nothing, Nada, Zip

I have found this the best way to teach The Null Factor Law:-

(Morbidly Seriously)

Come in quietly, sit down and open your books for a Multiplication Quiz. Anyone who gets 10 out of 10 gets a sticker. If starts off easy.

Question 1, 1 times 2.

(A few chuckles as well as suspicious looks.)

Question 2, 1 times 0.

(Some serious thinking, but confidently written answers.)

Question 3, 8 times (slight pause) 0.

Question 4, 300 times 0.

Question 5, 4 million, 600 thousand, 4 thousand, 7 hundred and ninety-nine times 0.

Someone answers, "Could you say that again?"

(We all have a giggle and I attempt to remember the number, amongst some disagreement)

(Serious Again) Question 6, X times 0.

Question 7, X + 3, in brackets, times 0. Oh, I better write that one on the board.

Question 8, (X+3)(X-2)(X-1) times 0. I'll write that one on the board too.

Question 9 ... (and so on)

This is the cool part! We revised a trinomial factorisation and had a 5 minute discussion about the resulting binomial expression when equalled to 0. Being equal to 0 meant the factorised expression was easy to solve. Then they tried some and BINGO! The success rate in the class was higher than ever before.

It seemed a very successful approach, highlighted by one person commenting, "Am I doing this right? This seems too easy."