There is a correlation between the two variables, but the team can't prove attending study skills sessions causes improvements in grades. However, experimenting with adding or subtracting the number of sessions offered and monitoring what happens to test scores may provide additional support of the hypothesis. The team can also juggle other variables to see if they have any impact. Remember scatter plots only show correlations. The team will have to depend upon members' knowledge and experience, as well as other data, to prove the hypothesis.
Scatter plots can be misleading.
For example, there is a proven correlation between children's reading abilities and how tall they are, but height has nothing to do with causing improved reading levels. Taller children are usually older and are at higher grade levels, hence, they are reading at a higher level. If there's no shape to the pattern, there's no relationship. However, if a pattern was expected and none appeared, it may be because the plot was constructed with too narrow a range of data. A scatter plot may require at least 50 data points before a pattern is discernable.