Okay kiddo, listen up! You know how sometimes we use math to compare things and see if they are equal or not? Well, when we say "proportionality" we mean that things are equal or related to each other in a certain way. But sometimes, things can change and not be related to each other in the same way anymore.
Let's use an example! Say we have a cookie and we want to cut it into smaller pieces to share with our friends. If we cut it evenly into 4 pieces, each piece will be the same size, right? That's because the cookie is proportional to the number of pieces. But what if we cut the cookie into 6 pieces instead of 4? The pieces might not be the same size anymore, and that's a deviation from proportionality.
It's kind of like a game of matching shapes. If we have a square and a triangle, we can't match them because they're not the same shape. But if we have two squares, we can match them because they're equal. When things deviate from proportionality, they're like the square and triangle that don't match.
So, in math, when we talk about deviation from proportionality, we mean that things are not equal or related in the same way anymore. We have to use different math rules to figure out how they are related instead.