Make sure to give students a great number of visuals, usually in the form of pictures or physical objects, when you are first working on digraphs with kids. The greater the number of concrete physical examples you can give students the quicker they will take up the skill. These are usually pre-reading skills, but we have seen a number of programs review these skills in a spiral up to grade 3.
The most common sh digraphs that we see are- prefix: ship, she, shower, short, shut. suffix: trash, bush, push, dish, and wish.