hi,

you need to understand that the normal distribution is a mathematical abstraction never to be seen in real-life. E.g. we say that the heights of people are normally distributed yet no one seriously believes that there are 10 m high people somewhere, with a vanishingly small but non-zero probability as well as people with 10 cm height.

Same with scores: it is a matter of judgment to decide whether the normal model is applicable or not . If the scores are high enough and the spread low enough so that they are in general far enough from zero then the normal model could be acceptable. If the scores are close to zero another, more right skewed, distribution could be a better choice.

regards