Precipitation
Precipitation is water that falls from clouds to the ground as rain, snow, sleet, or hail.
Think of it this way
Water droplets form inside a cloud the same way steam collects on a cold pot lid. The droplets grow heavy and fall down, just like water on the lid drips back into the pot. Rain, snow, and hail are all forms of this falling water.
Explaining precipitation by grade level
Rain is the most common kind of water that falls from the sky. Snow, sleet, and hail fall too. Different places get different amounts. Some parts of the US get a lot of rain, and some places stay dry most of the year.