Is it a p,b,d,or q ?

I have found that these four letters are very difficult for new English language learners.  I want to call these letters the compass letters, because they are all the same shape, just facing four different directions: north, south, east, west; like a compass.  Nearly all of my students struggle with these letters, especially "q" as you don't see it often, and moving forward I'll want to develop (or find) some games or activities to help my students differentiate between these letters.  I'm sure that the solution is repetition with sight words for each of these letters, but I know that it must be frustrating for my students to constantly make mistakes with these letters.  For those of you struggling with this problem I would recommend making lists of sight words (commonly used words) for each letter and reviewing them often.  These sight words should mostly be words that can't be replaced by the the first letter of one of the other three letters, for example: "pickle" would be a great sight word because there's no such word as bickle, dickle, or qickle.  For "q" it's easy because you just have words that start with "qu": question, quit, quality, qualify, qualification.  For "b" words like battle and battalion would be great and for "d" words like doctor, drunk and distance.  Try to make lists with sight words for every letter and review these lists until you know just by looking at a letter if it is a b,p,d or q.  Give me some time and I'll try to find a fun game for this activity as well.  Good luck :-)