I've always asked for little bit of work over vacation- or the child will disappear into a television/computer stupor for days on end. But I don't tell him what to do, and I haven't since he was 4. It's all his choice. Every vacation I make a "bingo" chart that we call "Brainy Bingo". When he completes a row, there is a prize- either a small trinket, a trip out for ice cream, time to make me play a game with him that I hate (his favorite reward), extra computer time etc. A full blackout on vacation earns an extra special reward (usually he picks what's for dinner and a movie).
I try to make the bingo chart parts fun. Listen to a read-aloud story, read for 20 min, do a craft project with me, play a math game on the iPad, bake cookies etc. - not things like 'do this terrible worksheet that will make you want to pull your eyes out!' Now that he's older, we make the chart together on the first day of vacation, incorporating some things he wants to learn (coding and programming) and some things he needs to work on (small motor skills, balance).
Often, if I don't push the issue, he'll do four or five things in a row happily. Some days it's only one. One is required to get on the computer but if he chooses not to be on the computer- I don't mention it.
