Dear Mr. Dad: My mom watches my 3-year-old son while I work part-time. I appreciate her help but it bothers me that she spanks him when he misbehaves or disobeys. I’ve been meaning to speak with her about this, but have been holding off because I can’t afford to hire a babysitter and I don’t want to antagonize my mom. What do you suggest?

A: Boy, that’s a tough one. On one hand, it’s comforting—not to mention more convenient and less expensive—to have your son cared for by a loving relative while you’re at work. On the other, if you and your mom can’t reach an agreement on how to discipline your child, you’ve got a real problem—regardless of the financial savings or the convenience factor.

There’s no question that kids misbehave (or do some boundary testing) from time to time—it’s part of their job. Your job is to put a workable disciplinary plan in place. I take it that you and your mom didn’t have this discussion before she started sitting. As a result, she may be using the only disciplinary technique she knows.

The two of you need to have the conversation you’ve been dreading right now. But be gentle. Start off by telling her how much you appreciate her help and that you know it’s not always easy to look after an active 3-year-old.

Then, let her know that while you believe your son needs to know that there are consequences for misbehaving, spanking shouldn’t be one of them. If she disagrees, tell her that research shows that spanking actually does more harm than good. Children who are frequently spanked are more likely to become anxious, depressed, and aggressive. They also get the message that it’s okay for bigger people to hit little ones. That’s why the American Academy of Pediatrics and other organizations have taken a clear, no-spanking-for-any-reason stand. I am betting your mom hasn’t thought much about the consequence of spanking your son. But once she knows what a bad idea it is, she may decide to reevaluate her approach.

That leads us directly to the next question: If spanking is out, what should your mom do if your son misbehaves? Well, first of all, you need to come up with a list of the kinds of behavior that are serious enough to warrant some kind of discipline, and the kinds that aren’t. In other words, what is truly bad behavior and what’s just harmless (though probably nerve-wracking) horseplay?

Once you do that, decide on some fair, non-physical consequence for each bad act. Ideally, you’ll get your mom to manage your son’s misbehavior the same way you do, so your son will understand that rules are rules, no matter who’s caring for him. That will reduce any potential “but mommy lets me…” or “grandma always….” arguments.

Time-outs can be effective—as long as they’re held to one minute per year of age—as are “logical consequences,” such as immediately losing privileges or special treats. But it’s important that you and your mom explain to your son exactly what’s going on and why.

You might also suggest that your mom find more outside activities or that she arrange playdates with your son’s friends. Some of his “bad” behavior may be the result of being cooped up with no one fun to play with.

Hopefully, your mom will be willing to make some changes. If not, you’ll have to look for alternate childcare arrangements. Your son’s safety and well-being are far more important than convenience and a few dollars.