## The DIY Christmas Tree – Surprisingly Mathematical

Oh, the sweet irony of living in a town that ships Christmas trees all over the nation (seriously, they helicopter them out by the bunch), yet I don’t have room for one in my house.

A few years ago, after seeing a few ideas of DIY space-saving Christmas trees on Pinterest, I was inspired to make my own (or should I say I was inspired to enlist my dad to carry out my vision?).

Supplies Needed:

• 4×8 plywood
• Hot glue and a hot glue gun
• Tree colored garland (I think I used 2 packages of this)
• Green, yellow, and brown paint
• Jigsaw
• Chalk Line
• Measuring Tape
• Pencil
• Picture hanging kit (both to attach to the back of the tree and to the wall)

I bought a piece of 4×8 plywood from HomeDepot or Lowes. I think it was around \$13. Again, it was several years ago so some of the details are a bit foggy.  I also got two packages of 30foot garland that looked like pine needles. It was super cheap, around \$10 for both packages. I already had all of the other supplies.

Here’s a copy of the original plan I had for my dad:

Originally, I had planned that I wanted the tree to be 6 feet tall and 3 feet wide, with a 6-inch stump at the bottom.

My dad had other plans, though. He said that we could reduce the amount of cutting we had to do if we rearranged where we put the tree on the plywood board.  This is how he suggested positioning it:

To simplify things even further, we decided to make the side length of the tree 6 feet, instead of the original 6.18ft. This slightly reduced the height of the tree, but it made for easier measurements.  The original side lengths and heights can be compared using the Pythagorean theorem, or trig if you wanted to!

Once my dad marked off the 6ft line on the left edge of the plywood board, he used his measuring tape to swing an arc around the cutting board, hinging from the upper left corner. Could your students figure out what the radius/diameter of this circle would be? Hint: it’s not 6 feet!

Once he drew the arc, we measured 3 feet across from the 6ft mark on the left edge. At this point, he brought out a chalked line (something I’ve never seen before!). He had me hold it from the upper left corner, and he pulled it to the 3-foot mark along the arc he just made. Once he had it taught, he pulled the string up a bit and then it snapped down on the plywood leaving a very visible, straight chalk line (burnt orange in color).

We then measured off 1.5 on the bottom of the tree, and then made another chalk line from the upper left corner down through the middle of the tree, continuing down a few inches further. Geometry vocabulary that applies: bisection!

We then were able to measure off the stump of the tree. I think I made it 3×6″ or 4×6″.

I used Microsoft Word to make a big star. I printed it, cut it out, then traced it on the plywood.

At this point, it’s time to cut out the tree and the star!

The next thing I did was paint the tree. I happened to have a bunch of dark green spray paint left over from an old project, so I spray painted the tree. For the stump and the star, I used some old Crayola paint that my parents have had since I was a kid (seriously, they’ve had that paint since I was 7 or 8). It worked like a dream!

After the paint is dry, I started to hot-glue down the garland to the tree, in a zig-zag pattern. This is the part that took the longest, by far. It was very useful to have a second person for this.

After all that was done, I hot glued down a picture hanger to the back, and hot glued on the star to the front.

Using just regular ornament hangers, I attached two strings of LED lights and some ornaments.

Here’s the finished project:

Also, right next to the tree I have a wax warmer going with a fir tree scent. It really brings the whole package together.

All in all, I think I spent about \$25 on supplies. I love how it looks (it really does look beautiful!), and it’s super easy to store when it’s not in season–I just hang it up in my garage.

I hope you enjoyed reading about how math unexpectedly showed up in my real-world DIY Christmas tree project.

-Audrey

A while back I made a display for special right triangles, and realized I never shared the files! You can download the PDF and the editable Publisher files here!  You’ll need to download the free font HVD Comic Serif Pro if you choose to edit the Publisher file yourself.

Here’s a picture of the pre-laminated pieces.  I took a few pieces of the finished product on my walls in the classroom, but each one had a nasty glare from the laminated finish.

Throughout the year, I will be adding more justifications as they come along.  The next batch that we will come across will be about segments.  From there, we’ll talk about angles, congruence, similarity, and more!

Here’s what I’ve got so far!  What justifications you most want to include in an edited list? I plan on using these primarily for two-column proofs in geometry.

## Trig Ratio Posters for Geometry and Algebra 2

This summer I’ve been busy making posters to spice up my very blandly decorated classroom. This is what my room looked like for my first year of teaching:

I don’t have a lot of wall space (the other two “walls” of my classroom are just windows), but I think I could definitely better utilize the space and make it much more of a usable resource for my students.  In the back (L-R, top to bottom) I had a poster on adding polynomials, the 8 mathematical practices, naming polynomials by degree, our bell schedules, naming polynomials by number of terms, adding polynomials, factoring trinomials, and the mathematical practices of habit and mind.  Some of it was very useful for a while, but didn’t need to stay up the whole time. Definitely more of a unit-specific anchor chart, than anything. Buuuuut, my walls were really blank, so I left them up for the rest of the year.

This summer, however, I’ve been making tons of posters to put up on my wall.  Well, tons of Algebra 1 and Algebra 2 posters, that is.  Geometry somehow hadn’t gotten any love, so I decided to remedy that by making a trig ratio poster.

I originally was just going to do the “big three” trig ratios since those apply for the geometry class, but I thought I’d add their reciprocals as well, seeing as they get used in Algebra 2.  I hope having them up at the beginning of the year will somehow help this information sink into their minds before we ever get to the actual trig units during second semester.