Here is a worksheet on differentiating the use of the adverbs farther and further. This is another document adapted from text found in Paul Brians’ book Common Errors in English Usage, which you may access for free at the Washington State University website.
What is the difference? Thanks for asking! Basically, usage sticklers insist on the use of farther for distances and further for extent of time or degree. Of course, in everyday discourse, these words are used interchangeably. In prose, however, the distinction might be well observed. In any case, one of the purposes of this series of worksheets (I have a hundred of them to post) is to help understand the concept of English usage, per the Common Core Standard in Language>Grade 11-12>1>b, “Resolve issues of complex or contested usage, consulting references (e.g., Merriam-Webster’s Dictionary of English Usage, Garner’s Modern American Usage) as needed.”
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.