This is a great first class lesson to warm up a new class. It's pretty fast, so depending on your class length, students might be able to take a project home on their first class, which I personally love.
It also involves cutting skills and fine motor skills so you can use this to gauge student abilities and modify future lessons from there. You can also teach/review symmetry and positive/negative space.
I found this lesson HERE on the 2 Soul Sisters Art Ed blog.
I taught this lesson to a Grade 4/5 class.
Start off my folding cheap manila tagboard in half vertically. Cut out three different sized hearts.
On scrap paper, color along the edge of the heart with oil pastel. Use a nice thick layer. We use Pentel brand but I think Crayola brand would be even better as I find it's much softer in consistency.
Place heart on white copy paper and hold down with one hand. With the other hand, use one finger to smear or smudge the oil pastel outwards onto the white paper.
Then start adding in the other sizes, encouraging students to create a symmetrical design
(flip over heart to the opposite side).
Some finished artworks- this took about one 40 minute period to complete.