Can someone enlighten me about standardised scores?

[MrsFogi]

We get these each year at my ds' school but I'm unsure what story they tell me year on year. Should I be expecting to see an improvement each year in his standardised score (and equally should I be worried if I see a big drop)?

[Tissie]

A standardised score is based on reseach with the specific test to see how students perform. Standardised scores are often presented on a curve. At the top of the curve is the score 100. This is the average score. on the left it decreases in units of 10 and on the righ it increases in units of 10. The vast majority of students or adults if they're being assessed fall between 90 and 110. Scores below 85 are a cause for concern.