Last but not least on this perfect summer afternoon in Vermont, here is a learning support on verbs and number. This is about a half page of text that leaves enough open field in the document to contrive a worksheet with it. In fact, since this document is formatted in Microsoft Word, you can do pretty much anything you need or want to with it.
This one, too, comes from Paul Brians’ book Common Errors in English Usage. This one, too, does a very nice job of explaining its central piece of procedural knowledge, how writers lose track of subjects in complicated sentences and often commit subject/verb agreement lapses because of that.
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.