Lauren: I just ran across this post today and since I started teaching Life Drawing when I was a graduate assistant 50 years ago, I'll set down a few thoughts.
In a class of first time students I try to assess where they are at when they come to me, so the first class may be without a model. I used to do it with a still life but these days I now have a couple life size busts and they work great for seeing just how a student has progressed with their abilities of observation. If a school has course outlines, what is taught will have to be followed. You may have to get creative as some "courses of study" can be a little stultifying. On the other hand, if these are private classes and this is the age level, the class can be very individual oriented.
These days High Schools have become quite sophisticated in what art students are learning and I have juried high school art that literally amazed me. However, much of what they do, (of necessity) is from photographs. Then you have to retrain their perception to encompass the third dimension.
A lot of what I teach is based on gesture and blind contour with a liberal amount of study from a skeleton. Good reproduction skeletons can be had from Dick Blick and other suppliers. They have some drawbacks, as in the way the parts are jointed, but they'll do. After students are a little more adept at getting the proportions right, I have them do "transparent" drawings of the figure with the skeletal structure indicated.
I have the greatest success with students when I can get around and with my own pad I carry around, I demonstrate problem areas and how to solve them. If the class is very large, alas, this becomes difficult to do.
Formulaic proportion is not introduced right away. I save that for later until their drawing perceptions have become more acute. Its possible that you may have some who have never drawn before, but usually they have had to take basic drawing. I have spent a lot of time in evening classes at a local community college and I have seen all levels of drawing ability. Those that have the most difficulty have spent a lot of time copying photos and have been told they are "wonderful". They are embarrassed when they experience difficulty drawing from life. These students need extra TLC as they can get very discouraged.
I'm sorry; I'm thinking I am rambling a bit. But I did say "a few thoughts". I hope this helps a bit. You are welcome to receive my Life Drawing Newsletter if you wish. I am always discussing various projects and showing student work. Just email me at email@example.com