One of the last big projects I did with the children this year was a flower study.  We looked at the work of Georgia O'Keefe and how she painted her flowers to fill the entire canvas.  We noted three things that Georgia O'Keefe did:

She painted the flowers to the edges of the canvas.
She used just 3 to 4 main colors on the flower paintings.
She painted a simple background.

The main objective was to get the children to draw huge flowers.  I stressed that their flowers needed to touch each side of the paper.
Drew the flower with pencil and traced it in a sharpie pen.  (Watercolor paper)

I gave the children three colors – either a cool palette (blue, green and purple) or a warm palette (red, orange and yellow).  I simply cut the colors off the strip.

For this second study – we moved from watercolor to tempera paints.  The drawing was the same – but no sharpie!  I used a heavy cardstock paper and cheap foam brushes from Michaels.  Again – I put out a cool and warm palette.
I used a foam plate for the paint – perfect with three sections.

We finished with painting flowers on canvases using acrylics.  Unfortunately, I failed to take photos!!  But the end results were beautiful.  You can buy panel canvases from Dick Blick very reasonably and I used the dollar acrylic paint from Michaels.  Here is a peek at a photo a parent took: