The letters "c" and "h" can sometimes be friends and work together to make one sound, just like how you and your friend might work together to build a tower with blocks. When "c" and "h" make this sound, we call them a "digraph" and write them as "ch".
You can make this sound by putting the tip of your tongue behind your front teeth and blowing out air while you squeeze your lips together. It's like you're pretending to be a train chugging along.
Words that have the "ch" digraph sound can be things like "chair", "cheese", or "church". It's important to remember that when you see the letters "c" and "h" together, they might not always make this sound. In some words, like "chemical" or "character", the "c" and "h" make separate sounds. But when they're friends and make the "ch" sound, it's always fun to say it loudly!