Q: Sometimes, when I try to explain to my 35-month-old the reason why we have certain rules (like no touching the stereo, or why we can't go to the park right now), she seems to understand and accept it. Other times, she just throws a tantrum. What should I expect from her regarding understanding limits?

A:  Between approximately 2 1/2 and 3, children begin to understand the logical connection between ideas—the "why"of things—which is the reason they start to ask "Why?" about almost everything! It is a major milestone in their overall development and in their understanding of how the world works.

However, this stage can also be very confusing and exasperating for parents. The inconsistency you’ve described in your daughter’s behavior is a perfect example. It’s due to the fact that a 35-month-old’s grasp of logic is still pretty shaky. One minute they seem very reasonable and wise and the next act totally irrational. This is coupled with the fact that children this age are not in full control of their strong emotions that can interfere with, and often trump, their ability to act as rational beings.

So when you tell your daughter she can’t stay up “super late” because she needs to have lots of rest for her friend’s birthday party in the morning, she may go right along with it. But when you tell her she can’t go to the playground today because it’s raining, she might completely lose it. You’re left feeling confused—why is one explanation harder to understand than the other? The answer is: It’s not. It’s just how an almost 3-year-old processes the world.

At this point it is best to explain the rule matter-of-factly and to be consistent in the follow-through. If your child throws a tantrum, validate her unhappiness/anger/frustration but don’t give in, as this will just make the tantrum a successful tool for her. It will also confuse her about what the rules really are. When your actions match your words, she will learn the rules much more quickly.

These interactions help set the stage for the negotiations she will try to engage you in from here forward. Just wait for the déjà vu you’ll feel in 12 years when you try to explain curfews. Until then, bear with your passionate 3-year-old, and rest assured that understanding logical connections and family rules is a skill that gradually unfolds over the next few years.