Inclusion order

Inclusion order is like playing with different sized blocks. You have big blocks and small blocks, and you can fit the smaller blocks inside the bigger blocks. But you can't fit the bigger blocks inside the smaller ones, because they won't fit.

In the same way, there are different sets of things (like numbers or shapes) and some sets have bigger things in them, while others have smaller things. If one set of things has all the things from another set inside of it, we say that the first set is an inclusion of the second set.

Think of it like having a big box and a small box. You can fit the small box inside the big one, but you can't fit the big box inside the small one.

In math, we use special symbols (like the sideways U or the backwards E) to show that one set is included in another set. This helps us understand how sets relate to each other and solve problems that involve them.