In Japan, children spend about 3 hours per week learning art in the first three grades. Learning to observe carefully and in order to draw, seems to be educationally important because the thinking and skills developed helps so much with their other learning. Of course drawing, like writing, is a useful communication skill in its own right. Writing to read is effective and drawing to see is similarly important. Some of the Japanese children's lessons also deal with imagination and fantasy.
Some projects are three-dimensional as well.
Be sure to do the activities and projects yourself before you teach the lesson. Make a list of the materials as you use them. It is best way to be sure you have planned for everything. Every experience is a chance get better. Make notes of successes and shortcomings.