The Student Growth Tracker is a great tool to measure student progress over time so it is helpful to understand how the scores are calculated.
To calculate the scores, we sum up all the points that were awarded to the answers, and we sum up all the points available for those answers (the point value on the questions), and divide the former by the latter.
For example, let's say a student completes just one formative with two questions. Question one is worth five points. Question two is worth ten points. The student get two points on the first question and six points on the second. Their score for that formative is as follows: (2 + 6)/(5 + 10) = 8/15 = 53%.
When multiple formatives are being calculated, all questions are considered and basically treated as if they were one big formative. For example, let's add a formative to our previous example. This formative has one question worth five points and the student earned four points. This student's overall grade is now as follows: (2 + 6 + 4)/(5 + 10 + 5) = 12/20 = 60%
This means that a formative or question with more available points will be weighted more heavily in the overall score.