The key things to remember are that the body MUST be on the breast at all the time and that all movements of the arms and legs MUST be simultaneous.
The action is one arm stroke then one leg stroke.
The arms are pushed forward together from the breast on, under or above thesurface. The elbows must be under the surface except at the turn. The hands are then brought back under the water but must NOT go beyond the hipline (except at the start and at a turn see below).
During each stroke some part of the swimmers head MUST break the surface of the water.
AT THE START AND AT EACH TURN. One stroke is allowed whilst submerged. The arms may extend beyond the hip line. A single dolphin kick, followed by a breaststroke kick is allowed whilst wholly submerged . The head must break the surface of the water before the hands turn fully inward at the widest part of the second stroke. The 15-metre rule mentioned in freestyle / backstroke DOES NOT apply. So if a swimmer is capable of travelling beyond this distance and it is to their benefit they can continue.
The feet MUST be turned outward during the propulsive part of the kick. The feet are allowed to break the surface of the water.
At the turn and at the finish BOTH HANDS must touch simultaneously on, under or above the surface.
When teaching get the swimmer to put their head forward. This gives an extra few centimetres on each stroke. Look for the shoulders and see that they are in line both horizontally and vertically. Check the legs are in line and the feet are pointing out.
The turns and finish also usually catch swimmers out and they tend to touch with one hand. Get them in to the habit oftouching two handed.
When teaching the key things are keeping the body streamlined and stretching the shoulders to give maximum length to the body. Look out for the hips swaying. The knees should not be bending like as if someone is riding a bicycle.