When we go to Boston, my kids like to eat a lot, lol. Things we don’t have as many options for where we live: seafood, Italian in the North End, cannolis, etc.
Spend some time walking around Faneuil Hall and the waterfront, if your child has never been.
The rest depends on how much extra time you have. Don’t want to be exhausted on tours. Speaking of tours, try to space them out. And take notes during/after each tour on your phone(s), because the visits will all run together in your memories, very quickly. I like to take a few photos on each tour, if I can do so without embarrassing my kids. I find that, if it’s ok with your tour guide, a photo that happens to have the tour guide in it, perhaps while they’re talking, will help jog memories of the vibe on that day.
I also like them to have lunch in the dining halls on campus, or eateries close to campus, where time permits.
If you happen to swing by the Lexington/Concord area at some point, Minuteman National Park has a nice presentation that’s offered something like every half hour. Jost a taste of history, not overwhelming and you can sit 