When students are not able to use both sides of their bodies with equal dexterity while performing fine motor skill tasks, perhaps each side (as in right hand or left hand) should be assessed separately. For example, if a student has one "good" hand and one which is not as coordinated, the actions of each hand could be assessed separately. It is likely that teachers will be testing by observation as well as outcome in an assessment such as this, so measuring each hand separately is certainly possible.
Another option for assessment is to measure improvement rather than completion for one or both sides of the body. This method or strategy can stand on it own as a final assessment or it can be repeated and eventually lead to completion and mastery of the task. Measuring each side of the body by time is also a possibility.
In either case, students can be assessed successfully despite the disparity in their body coordination.