 Pick up U1L11 from the side shelf.     Tonight’s HW: o HW #16 Pg. 113 #1-8; Do 20 more notecards with words you have not used from your vocab. list. (You should be studying these nightly.) 3 rd due on 9/184 th due on 9/19  Updates: o Unit 1 Quiz 4 (2.6, 2.7) 3 rd /4 th will be 9/22 Morning Geometry!

Agenda 1) Warm-Up! 2) U1L11 3) Prove THAT! 4) Cool-Down… Students who need to take Assessments: 3 rd Period – 4 th Period –

Warm-Up! Please take out your whiteboards! Solve the equation. Write a justification for each step. 1. 5r +2r = -3(r+4)

Warm-Up! Please take out your whiteboards! 2. Solve the equation and write its corresponding steps in the boxes to the right. (Use as many steps as you need.) StatementsReasons

Learning Objective By the end of this period you will be able to: o Write two-column proofs.

Geometric Proof (2.6) Guess what class…. You have already done proofs! Now, we are just putting all the pieces together We have so far written simple proofs by writing a sentence. Recall, Since ____ ≅ ____, by ________ theorem, ____ ≅ ____. AND recall, warm-up problem #1; writing justifications. Now, we are just writing everything in two-columns (#2 on the warm-up).

Geometric Proof (2.6) Two Column Proof o The column on the left are the statements, the steps of proving. o The column on the right are the reasons, the why’s or justifications. The reasons are in the form of a definition, postulate, property, or theorem.

Geometric Proof (2.5) You already have this written down in U1L10, but lets quickly review.

Geometric Proof (2.6) Brainstorm! With your tablemates take 1 minute to think of definitions, postulates, theorems, or properties you could use in proof #1. Record your thoughts on ONE whiteboard. Lets hear what you all said! Brainstorm! With your tablemates take 1 minute to think of definitions, postulates, theorems, or properties you could use in proof #2. Record your thoughts on ONE whiteboard. Lets hear what you all said!

Geometric Proof (2.6)

For practice 2, see if you can fill in the missing pieces of the proof.

Geometric Proof (2.6) Now, I think you all are ready! I am going to give you cutouts of two proofs (practice 3 proofs). The blue cutouts are the statements. The yellow cutouts are the reasons. See if you and your tablemates can correctly match up the statements and reasons for both proofs. (You will use each card only once and when you have completed both proofs you should have no extra cards.) When you think you have the proofs correct call me over and I will check. If they are correct you will copy the proof into practice 3.

Geometric Proof (2.6) You all are EXPERTS! You already have studied a lot of lines and angles this year, now lets add in some theorems that will help complete our learning. On the main whiteboard, lets see if we, as a class, can create a proof for this theorem! (Remember to be a theorem, it must be proved true.)

Geometric Proof (2.6) We already proved this! Practice 2b.

Geometric Proof (2.6) Take out your whiteboard and setup the two columns. Put your seat number in the top corner of your whiteboard. Go find someone with the same seat number and switch boards. On the new board you have right the first step.

Geometric Proof (2.6) Keep your partners board and go find another partner with the same seat number and switch boards. Can you set up the third step? Try your best One last time, go find a new seat number pal and switch boards. What is the last step of the proof?

Geometric Proof (2.6) This proof is very similar to Practice (2b). See if you and your tablemates can come up with this complete proof without my help. Good Luck!

Part 1: Cool-Down… Table-Share – In your tables answer the following questions. 0 Are you beginning to understand proofs? 0 If you understand proofs, what has helped you understand them? If you are still struggling, tell your tablemates why you are having trouble.

Part 2: Cool-Down… You all will have a blank proof on your table. Your job is to attempt to complete the proof as much as you can. IF you are having trouble getting started I will provide up to 3 hints.

Cool-Down… With the spare time in class I want you to continue writing notecards or completing your homework. If you are off task I will ask you to stay in during lunch.