The schoolhouse footprint is a little oversized. That dark bit to the west of the building is one of its walls. The building is casting a shadow on that wall, since the shadows are being cast NNW. You can play around with the imagery settings like brightness/gamma to hopefully help you see it. In this case you should draw the roof outline, and then move it so that its corners line up with where the building's corners meet the ground. I uploaded this change-set as an example of what the final result looks like. https://www.openstreetmap.org/changeset/152962551
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            #REVIEWED_GOOD #OSMCHA
            Published using OSMCha: https://osmcha.org/changesets/152921299
            