Amylase
Amylase is a substance in your spit that breaks starch down into sugar.
Think of it this way
Scissors in a kitchen cut a long bread loaf into small slices. Amylase works the same way — it cuts long starch chains into short sugar pieces. Starch arrives as a long block. Amylase breaks it apart, and sugar pieces leave as separate cubes.
Explaining amylase by grade level
Your mouth makes something called amylase. It starts to break down food as you chew. Try chewing a cracker for a long time. It begins to taste sweet because amylase turns the starch into sugar.