Duck test

The duck test is a way to figure out if something is what it seems to be. It can help us decide if someone or something is what it appears to be or not.

Here's how it works: if it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.

So if we see something that looks like a duck and it swims like a duck and it quacks like a duck, then we are pretty sure it's a duck. But if it looks like a duck, but it doesn't swim like a duck and doesn't quack like a duck, then it might not be a duck.