Grandma's Law

(aka The Premack Principle)

Work and then play

Part of 'adulting' is going to work to get a paycheck. Our children get little 'paychecks' all day long too. In general, the older the child, the longer they can wait for their 'paycheck'. If we structure things right we can use this concept to teach them new things and motivate them to do things that aren't so fun (does anyone really like doing the dishes).

We talked about First-Then statements and Positive Reinforcement in previous posts. The Premack Principle aka Grandma's Law is related to this. We're going to dig a little deeper to better understand exactly what we're doing so we can apply it more effectively.

What's Grandma's Law you ask? Well, for just a second, let's get technical. (We haven't done this since Positive Reinforcement!)


The Premack Principle is a principle of reinforcement which states that

an opportunity to engage in more probable behaviors will reinforce less probable behaviors.


You may have heard of this ABA strategy referred to as “Grandma’s Law”. The name comes from when Grandmothers, experts in child behavior, say to their grandchildren “You need to eat all your vegetables if you want dessert."

Here's a visual I made for you that explains it...

How to

Applying Grandma's Law is pretty simple. Is there something that you NEED your child to do? Is there something that your child WANTS to do? Put the two together in a statement ('First-Then' or 'Yes, when') and you've just used used Grandma's Law.

Want to make it even more effective? Follow these tips:

  • Hold on to your child's favorite things (phone, special toy, favorite movie or book). If they have free access to these things, there's no reason to do the 'not so fun things' (remember the dishes) that they NEED to do.

  • If it's a particularly unpleasant activity that your child NEEDS to do (like clean their room or eat Brussels sprouts) you may want to start with the WANTS to do in your statement.

  • Try and give the statement before your child says, 'no' or starts to protest. If you always do it after, you may be getting into the dreaded bribe territory.

  • If your child asks for something, you don't have to say no! You can say, "Yes, when [NEEDS to do], you can [WANTS to do]."


How about a real life example. My girls hate cleaning their room. I hate cleaning their room. It looks like a rabid pack of coyotes got in and made it their home. My girls also wanted to see the new Trolls movie, World Tour (very cute by the way with lots of jokes the grown ups can appreciate). So...it was time to have the conversation about cleaning their room but I really wanted to avoid the argument. This is basically how it went:

Me: "Hey, girls did you here the new Trolls movie came out? Want to watch the trailer?"

Girls: "Yes!!!!"

(We watch the trailer. They're super pumped about the movie.)

Me: "That looks good. Do you want to watch the movie?" (I cringe at this point because it's $20 to rent! But then I think about the 2 hours of time I'll get to relax...hah! I mean do the dishes, laundry, etc. that needs to be done!)

Girls: "Yes!!!!"

Me: "Ok, let's go clean your room and then we can rent the movie!"

Girls: "Ok!!!!"

With lots of help picking up and a few reminders about what they were looking forward to, the room is clean and they got to watch the movie.

Now, I can't possible spend $20 every time they need to clean their room. I'll add it to their evening routine to do before we read bedtime stories.

Your turn! How can you use Grandma's Law to help motivate your children?