Maillard Reaction
Maillard Reaction is what turns food brown and gives it new flavors when you cook it with high heat.
Think of it this way
When you put bread in a toaster, heat breaks apart the sugars and proteins on the surface. Those tiny pieces join up in new ways and form hundreds of new bits that cling to the bread. These new bits are brown and give off a rich, toasty smell that raw bread does not have.
Explaining maillard reaction by grade level
When you cook a potato, it turns brown. Heat changes how it looks and tastes. The brown color means new things formed. Each way you cook it makes a new taste.