Sometimes, the best back to school art lessons are the most simple ones. Here are some activities that might work well for that.
Here's a free worksheet that I put in my TPT shop so that you could download it. It is free, so go help yourself! Circle Drawing Game - Free Worksheet
A variation of this idea can be found at the Bay Area Discovery Center site. https://bayareadiscoverymuseum.org/activity/circle-game There are variations for a group activity and a solo one.
Here's another free worksheet that I just threw in. "What Can You Draw from a Circle?" You can download that at my TPT shop also. Click here for the free worksheet, "What Can You Make from a Circle?"
This next activity can be found on Tes.com and is called: “Drawing Game.” Here is the link:Circle Drawing Game Their idea is for you to recreate the images that they give you. You certainly could also let the kids use their imaginations to draw their own circle images.
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Here's a YouTube video titled, "How to Draw different things using Circle Shapes." It is more of a step-by-step activity.
One idea that I have seen around the internet is for the students to draw a picture that starts with one black dot. This would work for "Dot Day" or just an easy back to school lesson. This one is from Jill Bradley, Fine Art.
If you are looking for fully formed art lessons that anyone can teach check out my TeachersPayTeachers Shop, Art Sub Lessons. Here are some lessons that would be good for getting back in the groove of school.
"The Colorful Art of Bruce Gray" is a lesson with lots of circles and could easily work for back to school. Super easy and could be taught by parents, teachers or subs. Includes a lot of information and visuals about a contemporary artist. It is one basic lesson but could result in two separate art projects.
"Lines, Lines and More Lines" is a free lesson for preschool, kindergarten or first grade. All the visuals are there along with a script. It uses simple supplies. It could be taught by parents, teachers or sub. Fun and easy to do.
“Silly Sandwiches" is a fun lesson that can be taught to elementary, middle or high school as a beginning of the year lesson. Lots of fun!
"Negative and Positive Space" an easy lesson that could be taught to upper elementary or middle school, at home or in school. Lots of visuals and a full script for what to say.