It's a unmagnetized iron screw placed in the north pole of a U shaped magnet. I believe the region of least intense magnetic field is at the far left of the board. From what I understand the screw becomes magnetized and it's south pole is where it's touching the north of the magnetic, is it correct to assume the most intense magnetic field will be where the screw is touching the magnet due to there being direct contact between them?
Consider these images showing the magnetic field lines of a horse-shoe magnet. Magnetic intensity at any point in its field is directly proportional to its magnetic flux.So the region where the field lines are more densely packed have a higher intensity than where the field lines are loosely packed. If possible, draw the field lines for your own case and you will realize where the magnetic intensity is most and least.