I do not assign a certain amount of points each week. We use FIM in the classroom. I find that when they are trying to get a certain amount of points they play games beneath their skill level just to get the points. I am very big on the idea that the computer is a tool, not a toy in the classroom. I really use it as a tool to practice on level skills and challenge those who surpass those skills.
That being said, your child can always log in at home if he/she wishes to try to accumulate those points.
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