Hi Kate…thanks for using the Forum to ask your question. I guess I would begin answering you by asking you a few more questions! Let’s start with — what is your husband’s intention in taking up Yin Yoga? (I can imagine many possible answers, ranging from a desire to get more flexible to a desire to stop his wife nagging him to do yoga

. Or maybe he just want to spend more time with his wife. That’s a good answer too!) Depending upon his answer, your intention as his teacher can vary as well. However, let’s assume his attention is to regain and maintain optimal mobility—if so, Yin Yoga may be a great way to achieve his goal.
If I was the teacher of a student as you describe with the goal of building mobility, I may start by first having him do the Sit-Rise Test and note his score. Give him a couple of tries and take the average score. Note that score for future reference (you can track his progress over the months by seeing if his score changes.)
Then, I would probably choose one of the beginner flows that you can find in The Complete Guide to Yin Yoga or in
Yinsights. Start with shorter holds (maybe 3 minutes maximum) and just a one-hour class. Review all the options for students who have limited mobility: lots of props, but remember, we do want him to feel something. Over the weeks, teach him to fly his own airplane by asking him to figure out what is stopping him. Often people are stopped by compression and don’t realize it. They keep trying to go further, when there is no further to go! So, it is important to know when he reaches his final edge for that direction in that pose.
After a month of maybe 2 or 3 classes a week, try the Sit-Rise test again and note any improvement. Don’t be disappointed if there is little progress. He didn’t become tight overnight and it can take months to remodel fascial tissues. You can’t just take one shower and expect to be clean for the rest of your life, so encourage him to see his yoga practice as part of a life long health care habit, like brushing teeth. Even if he doesn’t regain a lot of mobility, consider how important it will be for him to maintain the level of mobility he has for the rest of his life!
I hope this helps you get started. Let us know how it goes.
Cheers
Bernie