1. Do Now:
Below is a proof given by a student. Evaluate the student’s proof by giving it a score out of 10 points, explaining your score (ie, what was good and bad about it).
Given: a v b
b=> ~c c
Prove: a

2. Aim: What strategies can we use to construct direct proofs?

3. What are direct proofs?
Direct proofs are the kind of proofs we’ve been doing. They build FROM the premises TO the conclusion.
There are indirect proofs (in which we use the contrapositive of the statement we are trying to prove), but we will learn about them later.

4. Remember:
If you are going to make a statement, it MUST be a result of a previous statement (Build from our premises!).
Where did this come from?
NEW INFORMATION comes from using laws!
Then you can USE that new information

5. What is a better way to write this proof?
Given: a v b
b=> ~c c
Prove: a

6. Collaborating on Proofs
Get into groups of 3. Each group will be given a proof to work on. Remember the tips we’ve talked about to write a good proof.
Once you have written your proof, you will trade with another group and evaluate their proof.