Give the students the sheet to write the letters of the alphabet. Afterwards check their sheets either on a one-to-one basis or by using the blackboard.
I notice common mistakes are getting b and d mixed up. Also forgetting Q or q. M/m and N/n are also mixed up by some students. Capital i and lower case i are also confusing for some students.
The Romaji version is based on the Japanese writing system. One sheet is for tracing and another is for trying unaided. I find the common mistakes are for chi,shi,tsu and ji. Not all the various combinations of romaji are here.
There are also some Romaji sheets that have all the combinations, a wee bit squashed but might be good for kids. One Romaji sheet with the letters written solidly and icons with Jupiter/Zeus is one I plan to have the students glue into the inside of their files to act as a reference. I intend to ask them to highlight the letters that are confused with kunrei: SHI,SHA,SHU,SHO,CHI,CHA,CHU,CHO,TSU,FU,JI,ZYA,ZYU,ZYO &JI . Some sheets I have made to trace and write in the Japanese equivalent.