my co-worker is chronically absent

A reader writes:

I work in a children's program part-time alongside another teacher who works the same hours as I do (about 10/week). We are the only 2 regular teachers in this program. Anyway, my co-worker chronically schedules appointments on the mornings we are scheduled to work. She has many crises in her life so between her and her children, she has many appointments. Historically she has done this in the past, but I thought that with a new director/boss, it would be a brand new start for all of us there.

Anyway, our director/boss knows about her upcoming appointments and we are scrambling around to get substitutes, but it's difficult for me to work alongside someone new every time we run a program because then I have to fill them in on what we're doing. It's difficult for the children because they don't know who's going to be there from one week to the next. In the next 3 weeks, she will only be working 1 program out of 9 scheduled.

What can I do or say to my boss and/or my co-worker? I did ask her the other day not to schedule appointments during the mornings we're scheduled to work (2 mornings/week!!). But I need some help in how to deal with this so I don't become negative about work. I want to enjoy my time there, not worry constantly about who's going to be there and who isn't.

Ideally, your boss would sit down with your coworker, tell her that the program needs to count on her being at work reliably, and ask whether, going forward, she's able to commit to being at work reliably, with absences only in rare circumstances. (And ideally she'd quantify "rare," since not everyone defines that the same way.) And she'd let her know that, while she's sympathetic to your coworker's situation, the job does require a reliable presence and if that's not realistic for your coworker right now, the job isn't the right fit. And then she'd stick to that, meaning that if the problem continued, your boss would replace her.

Ideally.

The fact that your boss hasn't done this indicates that either (a) your boss somehow doesn't know the extent of the problem or its history or (b) your boss is a pushover who isn't assertive about holding people accountable. 

You said that your boss is new -- is it possible that she doesn't realize the history here and thinks that your coworker's upcoming absences are an aberration?

If I were you, I'd talk to your boss, explain the duration of the problem, and explain the impact on you and the program. You want to do this calmly and unemotionally -- don't attribute motivations to your coworker, just focus on the facts and the impact. If you get the sense that your boss feels helpless to do anything about it -- which hopefully isn't going to be the case but, realistically, might be -- suggest that if she agrees that reliable attendance is an essential part of the job, she should find out if your coworker can meet those requirements going forward, and hire someone new if your coworker can't.

From there, it's in your boss's hands. At that point, you've done what you can do, and if your boss doesn't act, you probably need to accept that you have a boss who doesn't set standards and hold people accountable to them -- in other words, a manager who doesn't manage.