It is fairly common for young children to struggle with reversals, but less so for those reversals to be with the letters W and M. I have run into a few children this year who are struggling to master this concept. Attached in the PDF are 11 pages focusing solely on the letters W and M. The sheets are ready to go and include a "handy helper" reminder bookmark.
**PLEASE NOTE the sheets mention "rolling"...you will need to create a W and M dice for your student. I use small, unmarked wooden cubes and permanent marker. I suggest making several with different combinations of capital and lowercase M and W. I also suggest underlining the letters so the student understands the "top" from the "bottom."
Hope you find this helpful!