My 5th grader and 3rd grader have a set number of minutes to read each night for homework. Lucky for them, and me, they both love to read so this is one homework assignment that isn't a struggle. Both kids read at bedtime, in their beds after we tuck them in for the night. Because I'm not there keeping track of when they start and stop reading, they have to do it on their own. Sounds easy enough, as long as you know how to tell time. At the beginning of 3rd grade my daughter was still learning how to tell time with an analog clock which is the kind she has in her room. Rather than have her guess at the time, I had her draw me a picture of the clock when she started reading and then another picture when she finished reading.
The picture below shows her clock drawings one night. She started at 8:37pm and finished at about 9:15pm.
The following morning she brings me her papers and I write down her time.
This system has helped her take responsibility for this assignment and makes my life easier. I'd say that's a win-win.