There are several threads on here relating to assigning grades. Many teachers enter students' scores from the assignments directly. Most of those teachers allow students to redo the assignments for a higher grade. Many teachers also incorporate a "time spent learning" component to the grade. Typically I have assigned a grade based on the number of lessons that students master over the course of a unit, or semester. I tell them in advance what my expectation is for the number of lessons that they should master, and then base their grade on their corresponding "percentage of expected mastery". I assign a separate grade based on the number of minutes that they spent practicing, again based on a pre-determined expectation. Please let me know if you need clarification on this.

Here is one grading thread: https://khanacademy.zendesk.com/hc/en-us/community/posts/360018820592-OH-Did-anyone-grade-homework-assigned-on-Khan-Academy-

 Here is another grading thread: https://khanacademy.zendesk.com/hc/en-us/community/posts/360019016411-Grading-revisited

 One more that has some excellent suggestions: https://khanacademy.zendesk.com/hc/en-us/community/posts/360012792872-Grading

Great.  It would be great to see examples of how expectations are communicated to students (and parents).  (Letters?  Blogs? )

I don't have a letter or blog, but I do include Khan Academy assignments on the "Assignments" slide of my daily PowerPoint which is then uploaded to our Student Learning Platform where both students and parents are able to access it. Additionally I put the assignments into the grade book well in advance of the due date so that students and parents can see it on the horizon.