AROUND TOWN · SATURDAY, OCTOBER 17

The Great Give Back is a statewide day of service run through New York’s public libraries, and the thing that makes it work is that nobody asks you to sign up for anything. You walk in, you do a thing, you leave.

Four versions of it are running in the Town of Babylon on Saturday.

Lindenhurst Memorial Library, 1 Lee Avenue — 11 a.m. to 1 p.m., free. You write encouraging cards for the Marty Lyons Foundation, which grants wishes to seriously ill children. Each card written triggers a one-dollar donation toward a child’s wish. That is the rare volunteer task with an exchange rate.

West Babylon Public Library, 211 Route 109 — 11 a.m. to 1 p.m., free. Drop-in service stations, no registration. Teens can earn community service hours, which is worth knowing if there is a junior in your house with a form to fill.

Wyandanch Public Library — 11 a.m. to 3 p.m., free. An outdoor family fall festival built around the same idea: the giving-back part is the party.

Deer Park Library, at Deer Park High School, 1881 Deer Park Avenue — 1:30 to 3:30 p.m., free. The library sets up a table at Homecoming. Students in grades 6 through 12 drop off canned or boxed food and get a community service certificate. Food drive, football game, paperwork done.

A note on the weather, because it decides which of these you pick: Friday is the washout — showers and thunderstorms, a 90 percent chance of rain, gusts to 26 miles an hour. Saturday clears. Sunny, high near 55, but with a northwest wind of 17 to 21 miles an hour, which on a bay-side October afternoon feels colder than the number. The indoor card-writing table in Lindenhurst may be the smartest two hours of the weekend.

If you only have time for one: the card-writing. It costs nothing, it takes ten minutes, and it is the only one on the list where the thing you make in the room is the gift.

Sources: I Love Babylon events calendar · Lindenhurst Memorial Library · West Babylon Public Library · Wyandanch Public Library