This is for a handout to parents of a special education class. They speak no English, and the teacher speaks no Spanish. Thus general partial stock phrases are provided on the sheet and she translates only the activity needed.
In English the sheet would say:
I need to work on __.
In Spanish, would it work to say:
Necesito trabajar en __.
Keep in mind that it must be neutral and work for a variety of activities. Is the way 'en' refer to an activity equivalent to the English 'on'? Would another verb be better suited, such as 'practicar'?