When you attend school, attend camp, or attend a meeting, that means you go there. But when you attend to people or things, or when you pay attention to them, that means you listen to them, you give them your focus, or you give them your time, your effort, and your care.
So, attention is the act of watching, looking, or listening.
Your teacher might start class by saying "Attention, please!" or "May I have everyone's attention?" Those are polite ways to say, "Be quiet and listen to me." You'll have to pay attention in class—keep your eyes on your teacher, and keep still and quiet—even if it's difficult or boring.
We often talk about paying attention when people are talking to us or teaching us, but more generally, we also talk about paying attention when we're moving, working, playing, cooking, or doing anything else where we have to notice what we're doing and act carefully. Otherwise, we have accidents. Cady wasn't paying enough attention as she walked. Her inattention sent her crashing headfirst into a trash can. Whoops.
When you're paying attention to people or things, you're being attentive. If you're an attentive pet owner, you pay good attention to your pets, keeping them happy. If you're an attentive student, you'll learn a lot. Especially if you listen attentively, and take notes attentively.
It can be hard to be attentive. Does your mind wander a lot? Do you get distracted often? Me, too. This inattentive dog gets us. He's trying to listen to his owner, but so many interesting things are stealing away his attention.