Combine field values in slicer

[MintPolo]

I have lots of pupils in power query, and have managed to create a table similar to the following: 

The problem I face is that the subjects do not align. That is to say, Art can be in column "Subject 1" and "Subject 6". 

Each subject appears in Power BI as a separate field. I want the slicer to forego the need to expand subject 1 to see subject 2, but rather that it just says "art" and then shows me all pupils that take art. 

Is this possible? I considered looking at somehow aligning columns in power query, but thought this would be a monstrous task vs a hopefully simpler one at the Power BI end. 

I'm so painfully unfamiliar with DAX etc, or how to best use measures that I can't see a way round this problem myself. 

Thanks for your time and any help.

[DataInsights · Accepted solution]

@MintPolo,

You can unpivot the Subject columns in Power Query. Right-click Pupil and select Unpivot Other Columns. Alternatively, you can select each Subject column (multi-select) and select Unpivot Columns.