She wants to explore it. Get into everything. Well, she can't get into everything. There will be adults frustrating and forwarding those desires daily because some of the world will be touchable and some of the world just isn't. The toddler builds up the frustration in meeting those obstacles, the adult obstacles, over the long day at the same time that her ability to cope with frustration starts to wane over the long day.
Toddlers are very easy to redirect.
For example, transitions are typically very hard for all very young children but for some children transitions are especially hard. If I have a child who becomes very angry when I ask him to stop what he's doing, to leave the house, or to leave the party, then I'm going to try some strategies to short-cut the anger, like preparing him well. And then when it's time to leave, even if he's very angry, you need to leave. And it needs to be very consistent so that he trusts your ten-minute signal as real. Yes, well what really heats up during the preschool years, and by that I mean three, four, and five, is the amount of anger that will take place between friends.