These years of your child's time at school are called key stage 2.
At the end of each key stage, each National Curriculum subject has a target - your child should have reached skills, knowledge and understanding at a particular level.
Why have targets and tests?
Of course, some children may not make as much progress as others and some have Special Educational Needs.
As a parent or carer, you have a very important role to play in helping your children learn. The most important thing you can do is be interested in what your child is learning at school, and encourage them to tell you about it and explain it. Some parents are afraid of doing the wrong thing. Remember, you can never go wrong by showing interest in your child's learning. There are other things you can do too: this site gives ideas and tips for each subject. Don't feel you have to do all of them, but any you do find time to do will support your child's learning at school.
Ref: DirectGov : Parentscentre