Hand swapping throughout a task is not necessarily a sign that a child is uncertain of their dominant hand. It is a developmental stage for many toddlers and young children, but it is not ideal for children who have started school.
There two routes to tackling the hand swapping issue, the one to use depends on your answer to the following questions.
1. Does your child usually start with the one hand and then swap when that hand gets tired?
You can usually tell if this is the case because they may shake out or rub the tired hand and once it is rested go back to using it again. This is probably because their fine motor skills are weak. Through focused games and activities the muscle strength and dexterity can be gradually built up in the dominant hand, which in turn will build their stamina so that the hand swapping will reduce until they stop it altogether.
Once you are sure of dominance gently discourage swapping hands by taking a break from the activity and coming back to it a couple of minutes later using the preferred hand.
2. Does your child use their left hand if items are presented on their left hand side and their right hand if they are presented on the right hand side?
In toddlers and young children this is expected. In older children however it could mean that they have developed a delay in their skill to cross the midline point. This developmental bilateral coordination skill is vital to develop and can be addresses through a range of simple games and activities.