Imagination Mondays, a free weekly program geared to kids 2-4, runs at Union Square Plaza every Monday at 10 a.m. through Sept. 28, alternating between storytime and interactive fairy activities.

If you've got a two-year-old and a weekday to fill, Union Square is running a free program built for exactly that. Imagination Mondays happens every Monday at 10 a.m. at Union Square Plaza, 300 Powell Street (the corner of Geary and Powell), and runs through Sept. 28. It's free, no RSVP, all ages welcome but squarely aimed at the 2-to-4 set. Caretaker supervision is required at all times.

The format alternates week to week: one Monday it's storytime hosted by the Best Bookstore in Union Square, the next it's interactive activities with Happily Ever Laughter's costumed "Faerie Rosella." Here's the full remaining run so the morning doesn't surprise you — and note the next session is this coming Monday: Aug. 10 storytime, Aug. 17 fairies, Aug. 24 storytime, Aug. 31 fairies, Sept. 7 fairies, Sept. 14 storytime, Sept. 21 fairies, Sept. 28 storytime.

It's programmed by the Union Square Alliance, which runs the plaza's free daily amenities too — a Kids Zone with giant foam blocks and picture books, plus a borrow-and-return games cart open 9 a.m. to 6 p.m. — so a squirmy kid has somewhere to go before and after.

The logistics that matter: you're two blocks from Powell Street BART, so skip driving; garage rates down here are punishing for a one-hour outing. It's an open plaza, so there's shade only where the umbrellas are — bring a hat for a squirmy toddler. And the schedule is officially "subject to change," so glance at @unionsquaresf before you leave the house.

If I had a small kid and a free Monday: pick the storytime weeks if your kid will sit, the fairy weeks if they'd rather move, and get there a few minutes before 10 to stake out a spot.