[youtube http://www.youtube.com/watch?v=odepcD8i8R4&w=560&h=315]
Before kids can learn to crawl they need to work on the components of crawling. In addition to those components many of the kids learn how to commando (or belly) crawl first and in order to learn this they have to work on the same components. Two of the pre crawling activities that kids will do is pivoting on their bellies as well as pushing themselves backwards. This is their opportunity to explore movement and learn that they can cause movement from one point to another.
They start to put together using weight shifting through the arms/shoulders and through the legs/pelvis along with trunk sidebending and elongation. These coordinated movements will allow them to start moving in a directional way. When the kiddo uses pivoting they are using one side more than the other and when they use reverse movement they are able to use both sides of their body in a coordinated and equal way. This is different that doing things symmetrically (which means they use both sides in the same way at the same time). They are using their left and right side reciprocally so that a movement on the left will then be copied by a movement on the right and will continue to go back and forth. This reciprocal movement is a building block for crawling, walking, running, skipping, riding a bike, etc.
By pushing themselves backwards they are learning how to use their arms to help with movement. It takes less effort than pulling themselves forward (which becomes more efficient by the use of the legs to help). When the legs are incorporated for forward movement it not only involves reciprocal arm and leg movement but also contralateral coordination (i.e. left arm and right leg and then right arm and left leg).
We will cover more pre crawling development over the next few videos, so keep your eyes out for them.