A rainstick is a long, tube-shaped instrument that makes a soothing sound like raindrops falling when you turn it upside down.
Inside the tube, there are little objects like seeds or small beads that fall through the tube when you flip it over, making a clattering noise as they hit some spines that are inside the tube. These spines are made from toothpicks, nails or other objects that have been put down inside the tube. They cause the seeds or beads to bounce off the sides of the tube, creating a "rain-like" sound.
Rainsticks are often decorated with colorful designs or patterns, and they are made from different materials like bamboo, wood or plastic. They were originally used by certain Indigenous groups as a rainmaking tool before becoming a popular musical instrument all around the world.
So, imagine holding a long tube with little objects inside, flipping it over and over again to create a sound like that of raindrops. That's what a rainstick is!