What is a marching band exactly?
You can call them a group in which instrumental musicians perform while marching, often for entertainment or competition.
Oh that sounds hard! what instruments do they play?
Most times they play brass, woodwind, and percussion instruments.
What are brass instruments?
They are generally usical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips.
Can you give me an example of a brass instrument?
i do not know if an example but when you hear names like  "labrosones",  it means "lip-vibrated instruments".
Okay, it seems like it would be difficult to play these instruments and walk. How many people are in a marching band?
Well but Marching band play the and even Most marching bands wear a uniform