Here's a few events and activities happening Saturday and Sunday in the Bronx!

Head out to Crotona Park Saturday for a City Nature Challenge. NYC Parks is looking for people to help walk the park and observe and collect data. It's a friendly competition between cities around the world to see which is the most biodiverse. Things kick off at 11 a.m. for the free event.

Give old items you have a new home during a Stop 'n' Swap in Castle Hill. You can also pick things up for yourself, like preloved houseware, toys, books and more. It's happening Saturday from noon to 3 p.m. at 625 Castle Hill Ave.

At the Bronx Zoo this weekend, it's the annual Run for the Wild event featuring a 5K run and 3K family run/walk. The money raised helps protect wildlife. For those 16 and older, you need to raise at least $35 in addition to the registration fee to get a free all-day access to the zoo, free parking, a T-shirt and a medal.

How about some Weeding & Reading? This is happening at Fort Knox Park in Bronx Park. NYC Parks is putting this on from 9 a.m. - 1 p.m. Saturday. Bring your kids and while the adults weed, kids will read books that they are providing.

On Sunday, if you are in need of a helmet, get one for free! There will be a free helmet fitting and distribution event at Playground 52 on Kelly Street from 11 a.m. to 2:30 p.m.