I fed two ducks.
Why did you feed the ducks?
I thought they were hungry and I felt like they'd appreciate it if I fed them
That was nice of you.  Feeding the ducks can be fun and I'm sure they did appreciate it! It's good to make sure animals have healthy food available.
I remember in 4th grade I did this as well and then got upset because the ducks didn't say thank you.
That's a cute thing to think as a kid. I'm sure by now you've learned that ducks communicate in their own way, and it would be hard for us to understand how they feel. However, if the birds ate the food that you gave them, and they seemed happy afterwards, then they appreciated your kind gesture.