Polder

A polder is like a big bowl that people make in low-lying areas near rivers or seas. The bowl is called a polder because it’s made by putting up walls or dikes to keep the water out.

People use polders to control flooding and make more land that they can farm or build on. The water inside the polder is pumped out using special machines or windmills, so people can use the land for farming or building.

Think of it like this - imagine your sandbox is really wet and muddy after it rained. Your parents put up some small walls around the sandbox to make a bigger area to play. They also use a bucket and a shovel to scoop out the water and make the sand dry again. That's similar to what people do with polders, but on a much bigger scale!