A lesson like this on perspective with tulips has been around for eons. The students draw a line across the top of their paper, choose a spot for the vanishing point then draw a series of lines that from the vanishing point off the page.
I like to link this lesson to Vincent Van Gogh and our local flower fields. I tell the students a little about Van Gogh, we look at some of his art and then I tell them the history of the flower fields and we look at pictures of the flower fields.
Then they create their own version and try their hand at the perspective. I do this with first grade. This year, we did this with oil pastel and tempera cake. For some reason, we are just about out of blue pastel and I wanted them to be able to have a blue sky if they wanted to. I did order more blue pastels after this lesson.