Saying one thing and doing another, melting down over seemingly nothing, refusing to use the bathroom -- kids are contradictory little things sometimes. But before you throw your hands up and take your little one to a shrink, try to get to the bottom of those tumultuous thoughts. Maybe your child begged for a hamburger, then screams when you unwrap it, saying, "But I wanted chicken nuggets!" Or she's been talking about nothing but your upcoming trip to Grandma's, then wakes that morning and doesn't want to go anymore. There's a reason why kids may say one thing and do another. Kids can sometimes have trouble articulating what they want and need when there's a conflict between the two. For example, a child may wiggle and cross her legs while having a great time playing, but when you ask if she needs to use the bathroom, she denies the urge.
Or the child could be hungry but unwilling to stop the activity at hand in order to eat. Allow the child to make a choice in these cases - obviously, skewing the more attractive choice in favor of what you want them to do: "You may not want to take a bathroom break, but you'd rather not have an accident during your fun game, right?" In the case of eating, setting a firm mealtime can often solve arguments about coming to the table. Give the alternative of eating with the family or resting alone in her room. Do your kids seem tired but wired? If they're unwilling to go to bed, despite it being way past time, then their little bodies are probably producing excess adrenaline to keep them going. Heading off an exhaustion-related meltdown at the pass is the best way to prevent it. Again, establish a regular bedtime, and if it seems the kids are getting too tired before that bedtime, move it earlier. Kids thrive on routine, and when they can predict what's going to happen, they feel more comfortable and find it easier to express their needs.