Tonlé Sap is a big body of water in the country of Cambodia. It's a really special lake because it changes its size depending on the time of year. When it's rainy season, the lake gets much bigger and when it's dry season, the lake gets much smaller. How does this happen? Well, the lake has many rivers that go in and out of it. During rainy season, more water goes into the lake and less water goes out. This makes the lake get bigger! But during dry season, less water goes into the lake and more water goes out. This makes the lake get smaller!
Tonlé Sap is also a really important place for people who live nearby. A lot of people use the lake to catch fish and other animals, like crabs. They use special nets and traps to catch these things. And because the lake gets bigger and smaller depending on the season, different animals live in the lake at different times, so people can catch different things.
People who live near Tonlé Sap also build their homes on stilts, or really tall posts. Why do they do this? Because during rainy season, the lake can flood and the water can go really high. If people didn't build their homes on stilts, their homes would get flooded too!
Overall, Tonlé Sap is a really cool lake that changes size and is really important to the people who live nearby.