This post has been updated. Read it here, and get all the goodies to print and use in your own Geometry classroom: How To Teach Geometry Proofs: A Better Way to Sequence Your TwoColumn Proof Unit
21 Comments
Linda Mitcham
6/22/2015 04:03:32 am
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4/19/2016 10:45:13 pm
Thank you for this great post. I am teaching geometry (which I despised as a student) for the first time, and I appreciate the insights. Can't wait to try this.
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4/20/2016 02:29:06 pm
Hey Doc! :)
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Charles Vochatzer
5/25/2017 08:46:40 pm
I too did not like (despised might work) Geometry in HS. Now, next school year (201718) I get to teach it. Yeah! I'll be looking into getting lots of help with this.
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5/28/2017 04:53:22 pm
Hi Charles,
Terri
8/5/2017 05:23:11 pm
Also first year teaching geo in a long time with new text at a new school, ao looking forward to sharing and learning best practices!
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8/7/2017 02:52:08 pm
Hi Terri,
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Marilyn McArthur
8/7/2018 11:50:29 am
Great ideas. I for the most part have the same students for Algebra I and Geometry  so do try to "prep" them with algebraic proofs during Algebra course. One thing I do require when doing proofs is have also number justification  to correspond with statement. When not using templates they often are hard to match up.
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Becky Z
10/18/2018 09:48:44 pm
I have taught Geometry for the past 3 years, and started my career teaching Geometry from 1996  2003; so I am a veteran of the subject but still change up my technique every year that I teach it. This subtle interlude into proof writing is so clever, and something I haven't tried  I thank you and look forward to doing this lesson before simple Geometry proofs.
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10/22/2018 11:03:14 am
Hi Becky,
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Rebecca
2/12/2019 01:28:46 pm
Using substitution and transitive properties with the algebraic proofs makes so much sense when outlined above. Here's something I can never quite do a good job of explaining. The difference between when to use transitive and when to use substitution. Is one inclusive of the other? Meaning, any transitive property could also be considered substitution property? But not every substitution property is transitive? For example, in the proof just before Try It, could yo have used Substitution based on lines 3 and 5? THanks!
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2/12/2019 02:42:05 pm
Hi Rebecca,
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Chris Beggs
4/19/2019 09:54:33 pm
I agree with your "pet peeve"  I regard it as a "category error", segment AB is in the Geometry category, measure of segment AB is in the Arithmetic (or even Algebra) category.
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4/25/2019 12:11:01 pm
Hi Chris,
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Vicky
10/2/2019 11:52:27 pm
I am trying to download the Proofs Posters guide, but it will not send it to me because I already subscribe to your website. Is there anyway that you can resend those to me?
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10/3/2019 10:22:29 am
Hi Vicky,
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Kal C
5/24/2020 05:44:09 pm
Thanks for this. The style of proofs should be as logical as the proof itself. So I agree with your twocolumn poem structure, which is a systematic way to write a proof. It is essentially the same way that professional mathematics write their proofs, except in prose not in poem.
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Kal C
5/24/2020 05:52:43 pm
Sorry, for Step #5, disregard "using transitivity". That does not apply there.
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5/30/2020 02:31:44 pm
Hi,
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Brandon
1/21/2021 09:47:31 am
Is there, or do you have a complete curriculum for Geometry? I do not like the textbook style which is the typical format.
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1/23/2021 11:24:49 am
Hi Brandon,
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