She'll start to do new things, progress in her abilities with others, and reveal more of her personality. Though individual children develop at different rates, at around 21 months, you may see your little one do the following: Learn to hide and seek. Around this age, your toddler may love to play hide and seek games. Start saying no to you (but not always in words). Your toddler is starting to understand what others want and don't want, which helps her communicate her needs. For example, if she sees someone else getting a toy that she wants, she might say "me too" or shake her head no to get your attention. Take this opportunity to teach her about personal space. It's okay to tell her no, but never hit or punish her when she does something wrong. She should learn that it's not okay to hit or hurt people because that's against the law. Your child shouldn't be afraid to speak up if she needs something. If she's given enough time, she will usually tell you about it. For example, if she sees something interesting outside her window, she might make some noise to get your attention and then point out what she saw. You can talk about it later when you're in the car on the way home from your weekly shop! Some toddlers like to act big by throwing their toys around or acting like they're tough guy/girl. This isn't intentional behavior but rather an expression of their emotions.