Shapes can be difficult for children to master, as they need to be able to recognise what a shape is, how many sides it has, and roughly how big it is. Working out the size of shapes is something children accomplish early on in life, as most of them are given toys which require them to push shapes through the right sized holes. This helps children match shapes up with the holes they go through, which also benefits their 2D and 3D visualisation of the shapes whenever they come across them again later in life.
Parents can encourage their children's understanding of shapes and help them learn about them through different activities. One activity is drawing in a colouring book. These books have sometimes hundreds of different shapes to be coloured in, and all of them are completely different, exposing children to a massive range of shapes that they won't have seen or coloured before. The advantage of colouring books is that they teach children all about the sides of shapes, how many they have and how long they all are, as children need to keep inside them to draw properly.
As children grow they will be capable of different kinds of activities. Tracing can be quite difficult, but after a certain age children can cope with tracing shapes without many problems. Tracing shapes helps children to draw shapes properly, as they still might not be able to do so freehand. When they've traced a shape enough they will be able to draw it on their own, and begin drawing other objects that are more complex and imaginative.
Parents can help their children understand shapes better by using them in certain tasks they do throughout the day. When they're loading the washing matchine they can point out that the machine is a cube, asking them to see if they can draw it. The same can be done for the door, a circle, which is much easier for children to draw. By doing this and giving lots of praise when children make a real effort, parents will be encouraging the understanding of shapes much more.
There are shapes everywhere in day to day life, and they can be picked out very easily. Playing a game of eye spy with shapes will help children pick out these shapes wherever they are, until they walk along listing every shape they see to their parents.