Balsa is an extremely lightweight wood that comes from a fast-growing tree native to Central and South America. Despite being one of the lightest woods in the world (it can actually float very high in water), balsa is surprisingly strong for its weight, which makes it perfect for building model airplanes, boats, and rafts.

Balsa wood is so soft you can dent it with your fingernail, and you can cut it easily with a regular knife. Its pale, creamy color and smooth grain make it easy to work with. Because balsa is light but sturdy, engineers and inventors use it for testing new designs: if you want to see whether your bridge design will hold weight or your airplane design will fly, building a balsa model lets you experiment without needing expensive materials or complicated tools.

Today, balsa remains popular in hobby shops, where kids and adults buy thin sheets or small blocks to bring creative projects to life.