Look at your child's posture and the furniture they use when sitting at a table to write or play on a computer. Is the chair too high, leaving the feet dangling? Is the work surface too high, leading to raised upper arms and hunched shoulders? If so, telling children to sit up straight won't work.

If you can't find a chair that fits, put books under the child's feet, so they are in contact with a surface. If the work surface is too high, create a firm wedge-shaped cushion on the chair. This will give the child height so he can work with elbows at his sides and in line with the work surface, rather than up in the air. The wedge shape, tipping the child slightly forward, will also promote good sitting posture.

Lead by example: if your children see you slouching, they are more likely to do so themselves. Family stretching sessions are a good idea. The basic principles are to stretch muscles to the point of tension, not pain. Short, repetitive sessions are more effective than occasional marathons. Never hold your breath while holding a stretch.