Lesson 1: Lines, Ellipses and Boxes
Ellipses in Planes
Put an ellipse in there. That's all.
It may look simple, but there are some pitfalls to watch out for. Don't worry about anything aside from getting the ellipse to be smooth and evenly shaped, and having it touch all four edges of the plane as snugly as you can manage. Of course, draw through your ellipses (as mentioned in the table of ellipses exercise).
Be sure to make use of the ghosting technique - this should of course be applied to every mark you put down, but it will especially help you here. Don't worry if you mess up - you'll have plenty of planes to practice with.
Purpose of this exercise
This exercise is just the beginning of something much more complicated. In the future, we'll be tackling constructing cylinders inside of boxes, and other similar challenges, and these will come with additional criteria that will need to be met. The purpose of this exercise however is just about maintaining the smooth, even shape above all else. That is your first priority. Second to that is, as mentioned above, fitting it snugly within the plane, touching all four edges. Given that these are generally awkward shapes to work in, I frequently have students who start deforming their ellipses, getting generally overwhelmed by the difficulty of the task.
More than anything, it's an exercise in calming down. The difficulties faced here are generally more of one's own making. Take it easy, and just try your best to drop a nice, even ellipse in there.
Mistake: Deformed ellipse
This is a mistake I see frequently. See how the ellipse is bumpy and wobbly, and it kind of reaches out to touch the edges rather than maintaining an evenness to its shape? Avoid this. As mentioned several times above, maintaining a smooth elliptical shape is critical and above all else is your first priority.
Mistake: Floating ellipse
I also see this every now and then, though less frequently. While getting the ellipse to touch all four edges is your second priority, it is still something you should strive to do. It's pretty clear that with this example, no attempt was made to achieve that goal, and the ellipse - though evenly shaped - was just plopped in the middle rather unceremoniously.