I like to teach Math tricks because I think Maths can be also funny :)
Step 1: Multiplication Tables
Multiplication tables are often hard to learn for children, so tricks can be used to help.
The most difficult multiplication seems to be 7x8. It can be learnt this way: 5-6-7-8 -> 56 = 7x8 -> 7x8 = 56
Someone found multiplication table of 9 difficult, but when I was a child, my mom taught me this trick, the "stairways" or the "elevator":
The digit of the tens goes up, the digit of the units goes down.
Step 2: Joke to the 8
Now we're making a joke to the 8. Lets pretend 8 doesn't exist and write down all the digits from 1 to 9. You'll get this number:
Now multiply this number for one of the results of the multiplication table of the 9, from 9 to 81. You'll obtain a number that's have only one digit, and that the one you multiply the 9 for in the number you choose.
Step 3: Pyramid of 1s
This is simpler to understand just looking to the image. :)
Step 4: Music
This is not mine, but I think it's wonderful: Song from π!
Step 5: Pythagoras's Theorem
Pythagoras's Theorem demonstrated with water (not mine), for older pupils: