I recently did this lesson with my third graders. We began this lesson by listening to Jazz music. I asked my students to try to visualize the music while it was playing. We then discussed ways to show rhythm and movement in art. 
For this lesson, I taught my students to draw a guitar. After this, students were asked to draw designs or patterns to show rhythm. We then used warm and cool colors to paint our pictures. 
These turned out really nice. I can almost hear the music now.
I found this great lesson on Deep Space Sparkle, however I have seen similar lessons posted on many other sites. 
Birch trees are great because they are simple. To begin this lesson, we drew a horizon line and painted the sky with watercolors. Then on a different piece of paper, we drew several trees. On half of the tree we painted a gray shadow. We then use black paint to draw small lines on the tree. After this, we cut the trees out, and glued it to our painting. We then used gray watercolor to paint a shadow in the snow. Lastly we added falling snow by splattering white paint.
When I heard that my fifth graders were learning about the Vikings in Social Studies, I thought it would be a great time to do a Viking ship lesson. These Viking ships were done on tooling foil. After creating the design on the foil, we added a bit of black ink, which we gently wiped off with a paper towel. This made our drawings look antique. Finally, we glued these to a black piece of paper and painted designs in the border with metallic paint. 
I think these turned out nice.
It felt really nice to spend an entire day painting something for myself.
Amazingly enough, this was my first time doing a tessellation lesson. I am not very good at math, and I find tessellations extremely difficult. However, I decided that this year I was going to challenge myself to teach it. To begin this lesson we look at the artwork of MC Escher. My students are always amazed with his work.
To make tessellations a bit easier on myself and my students, I had them create a stencil. I gave each child a small rectangular piece of paper with a grid on it. I had my student draw one shape along the side and one shape along the bottom. These shapes were then cut out, and placed on the opposite side. If you use the grid, it is much easier to make sure the shape is placed exactly opposite. Once this is in place, use a piece of tape and secure it. 
After the stencil is made, I had my students trace it onto their paper. Students then draw details such as eyes, scales, hair, etc. 
Students then outline everything with a black crayon. After this, all they need to do is color their tessellations. I had my students use liquid watercolors for this part.
These turned out great, and it really wasn't hard to do. Tessellations were not as difficult as I thought they would be.