Species
Species explained in an easy to understand way:
Imagine trying to pair socks after doing laundry, where only matching socks form a proper pair. Just like how only socks that are similar enough can be paired to form a useful set, a species is defined as a group of similar organisms that can breed and produce fertile offspring. The connection here is that just as only socks that are designed to match can function together as a cohesive pair, only organisms within the same species have the right 'design' to successfully reproduce and create fertile offspring, maintaining the continuity of their species.
Practice Version
Species: A group of similar organisms that can breed and produce fertile offspring. Species. In simple terms, a species is a group of living things that can have babies together, and their babies can grow up to have their own babies.