Google+

### Congruent Triangle Gazebo -- Geometry Class Project

One of my goals now that I'm teaching is to share some of the projects I am doing with my classes. Before break I was teaching my geometry classes the congruent triangle shortcuts: SSS, SAS, SAA, ASA, and HL (for right triangles only). In one class I assigned a congruent triangle project. I gave the kids the choice of building a truss bridge, making a gazebo, or making a congruent triangle picture that had at least five different pairs of congruent triangles (one for each shortcut) and they needed a page showing each of the pairs as congruent with one of the shortcuts or needed to mark them in their drawing. Most of the kids picked the drawing. I wasn't in love with the gazebo tutorial, or the gazebo made in it so I thought I would make my own. Today I am going to share my gazebo as well as a project sheet to assign it. (I am still deciding if I am going to assign it to my other class or not as they are about half a chapter behind the other one.)

I wanted all five shortcuts to be clear on my gazebo. I also wanted all five to be there. The tutorial video one I found only had three of the shortcuts.

I love that this gazebo starts with a geometric construction. If you have not taught your kids to do constructions, you could always provide a regular hexagon template for the base and ceiling. I covered mine with a piece of the Tie-Dye Gift Wrapping Paper which I reviewed previously. You literally cut three hexagons out of cardboard and cover them (two glued together for the base) with wrapping paper. In my project sheet I mention if you use plain paper to cover them you can draw the equilateral triangles that form a regular hexagon to add even more congruent triangles.

The columns, railings and roof are made from pieces of tightly rolled (and glued shut) pieces of cardstock. They are hot glued into place. I left only one opening so I could have all five of the shortcuts represented. The below railing decorations are different pairs of congruent triangles. The shortcuts that are represented by each are labeled on the top with markings to show the congruent parts that make the shortcut.

I tried to use vertical angles and reflexive property sides in them since the kids have to notice these to use the shortcuts in problems and proofs. The kids get to design their own triangle decorations as long as they use all five shortcuts. This of course means one pair has to be right triangles to use HL or hypotenuse-leg.

It is amazing to me how sturdy my gazebo is considering what it is made out of. It also really did not take that long to make once I sat down and did it. I cut my triangle pairs by folding the paper and cutting them so I was guaranteed they would be congruent.

I even showed that SAA is the same as AAS on my gazebo. I love how this summarizes all the shortcuts in one place plus gives the kids hands-on building and creativity.

So if you are looking for something fun to add to your congruent triangle unit, grab my project sheet (you can make it your own since it is a Google Doc) and start building! I am thinking I may add a triangle banner to the top of the entrance with "Carrie's Congruent Triangle Gazebo" on it. That way the kids will have a place to add their names!