Day

A day is what we call the time it takes for the Earth to spin around once completely. Imagine a very big playground ball we like to play with. If we spin that ball around really fast, we can watch it spin around and around for a long time. That's what the Earth does every day, it spins around and around like a top.

As the Earth spins, we get different amounts of sunlight on different parts of the planet. That's why some places have daytime while other places have nighttime. When the side of the Earth you're on is facing towards the sun, it's daytime where you are. And when the side of the Earth you're on is facing away from the sun, it's nighttime where you are.

So, a day is the time it takes for the Earth to spin around once completely and to experience both daytime and nighttime. It's what helps us keep time and know when to wake up, go to school, eat lunch, and go to bed.