Is it a sin to skip work because I can't go around the time they planned me in?

It is not a sin but it is irresponsible.

A lie is a lie, not mortal. Why cant you call in and be honest? You may lose the job but you will feel better I bet.

According to the Bible, a lie is a lie & lying is a sin. Your boss will know that you’re not really sick & will know that you’re lying so you can go to your driving class. He/she feels that being at your job is more important than driving classes. By being irresponsible & lying to get off work when you were told you were needed could mean that they will fire you for not showing up at work when scheduled. IF by chance they don’t fire you, your credibility will be lost & they won’t ever believe anything that you have to say. Why can you not go to the 2:00 driving class & be to work by 3:00??? Or, is there not another instructor who could work you into the schedule you need???

Yes. You may not be cursed by “God” but your boss may find out and that will be WORSE!
Honesty is always the best policy!

You’re a responsible person with a very strong sense of right v. wrong. If not, you wouldn’t have posted your question; you would have called-in sick and not cared. But, you do care. You’re struggling with this matter. And, I’m guessing that your moral fiber makes you a bad liar.

Can’t you talk with your boss about getting that one day off for driving instruction? Perhaps you could even swap that day for another day. Speaking as an adult, I respect and want to accommodate anyone who’s honest with me.

Not sure it is a mortal sin, but it isn’t what the bible says we are to do. If possible, I would do my calls and change things around before work or on a day off. Another option you might have is to swap shifts with another employee for a few days. Most bosses don’t care as long as someone is there.