From Paul Brians’ book Common Errors in English Usage, here is a worksheet on differentiating and using properly the adjectives ignorant and stupid. This is a full-page worksheet with a two-sentence reading and ten modified cloze exercises.
Given the current state of American culture and society, I would think this would be timely, and therefore useful, material. But that’s just the perspective of my currently jaundiced eye. On a brighter note, and to give credit where it is so amply due, you should know that Professor Brians allows access to his usage manual at no cost; you can find the webscript (can I coin that portmanteau?) at the Washington State University website.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.