Flip

You could focus on one part of the F, or just one point. Where that will be on the grid once you have flipped the F? Can you build up a picture of the F after the flip in this way?
You might like to have some dotty paper to hand to draw the F after you've talked to someone else about it.
You could draw the grid and the F on an overhead transparency, then flip it to check what you have pictured in your head.