There are two main ways to get your class working handson with Geometry concepts. Try manipulatives, software, or a combination of both.
Check out Geogebra for a great techapproach to inquiry learning. To use the software in a lesson, have students create the diagram (or use a template). Be sure all measures are displayed. Then, as students manipulate the points, lines, and angles, they can observe how the measures change in relation to one another. For example, to discover properties of angles along a transversal, your students can quickly sketch a pair of parallel lines on the screen. Then, after drawing the transversal, they can label all angles and have the software display the measures. They will notice congruent pairs right away. Then, as they drag the transversal and change the diagram, the angle measures will keep updating. The students will see that certain pairs of angles are always congruent and certain pairs are always supplementary. Have students write these observations in complete sentences. I often have my classes write their rules in an "if___, then ___" format. I also have them give their own examples.
If you do not have access to technology, or prefer to follow it up (or mix it up) with a handson activity, the same properties can be discovered by hand. Have your students trace an angle, then slide it down the transversal to overlap perfectly with its corresponding angle. They can discover Corresponding Angles Postulate, and then move on to make observations about Alternate Interior & Exterior Angles.
The key is really just to avoid GIVING a theorem or property any time that you can. When students discover it for themselves, they can remember it, understand it more deeply, and apply it more smoothly in the future. You can use patty paper for this, but I usually just cut up tissue paper or tracing paper.
You can also have your class measure the angles with a protractor. They can draw a few diagrams and record angle measures and observations when the lines are parallel and compare these to similar diagrams where the lines are not parallel.
Be sure that each student records observations in complete sentences and then develops a property also written as a sentence. I do a similar setup for teaching vertical angles. Using a small piece of tracing paper, the kids draw a pair of intersecting lines. By folding different ways, they can see pairs of congruent "overlapping" angles.
I use an inquirybased introduction for Triangle Theorems as well. For Triangle Sum Theorem, there are plenty of options:
1. Use Geometry software to sketch a triangle and display its measures. Find the sum of the interior angle measures, then drag one vertex to create a new triangle. Find the sum again. (Repeat) 2. Use a protractor. Draw a few different triangles with different classifications (right, obtuse, etc.) Measure the angles and find the sum for each triangle. (There will be some error with this method, so I have students do plenty of examples and notice that their sums are all approximately 180 degrees.) 3. Use cutup paper triangles and have students line up the vertex angles to create a straight angle.
I do Exterior Angles Theorem in a similar way.
A few tips:
Looking for more detail or more examples??:
Here are links to some of my Geometry specific inquiry posts to get you started  1  How to actually structure an inquirybased lesson plan 2  The specificbenefits of an inquiry approach 3  Questioning strategies for inquiry learning 4  Discovering Congruent Triangles 5  Discovering Impossible Triangles 6  Discovering Surface Area (middle school) 7  Discovering Segment Addition Postulate Or, click any of the images above to purchase worksheet packs and materials to accompany your lesson. Have you subscribed? I'll send you great stuff!
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15 Comments
Sara
1/19/2016 09:22:58 pm
I used the markers for triangle inequality theorem today in class. Students loved it!! They were getting it right away. Because of the time and space constraint of my classroom, we did this as a whole class/discussion activity. Still worked really well; even with my "bad" class.
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1/20/2016 09:29:50 am
Awesome! Thanks so much, Sara! Love to hear that your class did well with this. :)
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Helen
9/17/2016 06:05:01 pm
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Supriya
1/10/2017 11:38:58 pm
Your ideas and material is amazing....I just loved it..I am using it for my students. I also want to know that you have any stuff for preschool kids...my daughter is 5 yrs...I want some material for her...thanks
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1/13/2017 12:37:47 pm
Hi Supriya,
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rose nagy
10/2/2019 11:01:37 am
please sign me up
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10/3/2019 10:24:20 am
Hi Rose,
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10/21/2019 12:58:59 am
I solved the problem of the triangle inequality theorem using the method of using the oil points as you instructed. It is really effective for my study of geometry math, both simple and easy to remember.
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Debbie
9/24/2021 11:39:49 am
My daughter is having trouble with constructions such as bisecting an angle. We've gone over why it works, and she can follow the reasoning, but when it comes time to test, she can't remember how to do it because she doesn't really OWN it. Any suggestions as to help her with constructions would be greatly appreciated. Thank you.
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9/24/2021 12:26:49 pm
Hi Debbie,
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11/23/2021 04:45:15 am
My little boy having a hard time to figure this out, luckily I found this. I'll use this as guide to explain to him. Thank you!
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Christine
7/5/2023 11:59:54 pm
Good Evening,
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7/10/2023 10:35:05 am
Hi Christine,
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Ashley
9/18/2024 07:32:43 pm
Where can I find the worksheet where you rip the angles of a triangle to prove the equal 180 and show how to remote interior angles equal the exterior angle? In the picture the wkst is orange and the triangle is blue.
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9/24/2024 10:16:47 am
Hi Ashley,
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