All math is related in some way, but I believe this unit, Reading and Interpreting Data, might be better suited to Statistics. There is a section, "Comparing dot plots, histograms, and box plots", where there is no prior foundation. The student is asked about the "mean" of the data. Mean has not been introduced and explained. Histograms, dot plots and box plots (whatever they are), appear to have no relationship to "Pre-Algebra". This is just my opinion and in no way a criticism of Khan Academy. 

Can someone shed light on why this Unit is in Pre-Algebra?

Michael