How to do it...

To complete this recipe, do the following:

1. Create the following measure:

InCommon = 
    VAR __Students1 = 
        SELECTCOLUMNS(
            FILTER(
                ALL('R02_Students'),
                'R02_Students'[Teacher] = MAX('R02_Teachers1'[Teacher])
            ),
            "__Student",'R02_Students'[Student]
        )
    VAR __Students2 = 
        SELECTCOLUMNS(
            FILTER(
                ALL('R02_Students'),
                'R02_Students'[Teacher] = MAX('R02_Teachers2'[Teacher])
            ),
            "__Student",'R02_Students'[Student]
        )
    VAR __InCommon = COUNTROWS(INTERSECT(__Students1,__Students2))
RETURN 
    IF(ISBLANK(__InCommon),0,__InCommon)

2. On a Report page, create a Matrix visualization and place the Teacher column from the R02_Teachers1 table into the Rows area.
3. In the same Matrix visualization, place the Teacher column from the R02_Teachers2 table into the Columns area.
4. In the same Matrix visualization, place the InCommon measure into the Values area.