“Each of you is perfect the way you are ... and you can use a little improvement.”
When a small child is angry, we can tell! They may lash out, hitting or kicking to express the uncomfortable feeling they're having. They may yell or cry. The feeling they are having is important! It tells them there's a problem. As children develop, they can learn to understand the feeling and take care of it without necessarily acting it out.
We help them to do this by listening to and acknowledging their feelings. We help them recognize the discomfort that underlies actions by slowing down, getting on to their physical level, and being interested in their feelings. We attune to their feeling, providing the template for them to become aware of their own feelings. Over time and with support, their awareness grows so that they can choose how to respond to the feeling rather than act on it impulsively.
At the same time, we can and should help children to stop their bodies from hurting us or other people. When a child has an angry outburst, we have an important role. We can stay close to them, setting a limit by holding them in a firm and loving way. "I'm here, I'll sit and hold you until you're safe to stop kicking." We can offer an acceptable alternative to hitting--"Here, I'll hold you and you push my arms as hard as you can. Now pull." This allows them to use up the physical energy that comes with being upset without hurting anyone. We can help them to take big breaths or do lion's breath to channel the energy. Children can learn practices that help them handle their feelings.
Each child's nature is perfect and wonderful. They come into the world needing support, though, needing loving connection and guidance to handle the complicated feelings and ideas that come up in them. That's part of the 'little improvement' that Shunryu Suzuki speaks of. Adults are the same, already wonderful and needing a little improvement through love, guidance, and support.
As a mom (to 2 teenage sons), wife, and person in the world, I have been on a long imperfect journey. I have made many mistakes, but with mindfulness, emotional reflection, and lots of support I have learned enormously from those mistakes.