Square roots can be a confusing concept. They can be especially tricky for younger students (e.g., middle schoolers) who may not be developmentally ready for the concept, for students who have difficulty making connections between concrete and abstract concepts, and for students who have difficulty visualizing information.
I've found that a multiplication table can be a great tool to help students visualize the relationship between squares, their sides and areas, square numbers, and square roots.
Here are some activities to consider:
SOLVING MATH PROBLEMS BLOG
Blending her backgrounds in mathematics education and educational/school psychology, Adena offers an integrated perspective to understanding and supporting students who struggle with math.