3. The content of this lesson will be on number (not shape). Writing proofs can be very difficult, especially for those people who rush maths (lazy people) and like to calculate things as quickly as possible. These people understand the process but not always the reasoning.

4. What is a proof? A proof is an explanation to prove something. It isn’t something that can be answered in sentences or something with only calculation. Both are necessary. Let’s try an example.

5. Prove that 17 is an odd number. Odd numbers are numbers that end in 1, 3, 5, 7 and 9. Plan: Calculate the nth term for the sequence of odd numbers and prove that 17 is within it. Sequence (ascending) of odd numbers: 1, 3, 5, 7, 9, … Let n be the position in the sequence above. The nth term is _______. 2n - 1

6. Sequence (ascending) of even numbers: 2, 4, 6, 8, 10, … Let n be the position in the sequence above. The nth term is ____. 2n