A ratio compares two quantities, like 2 spoons of blue paint for every 3 spoons of yellow. We write it 2:3 or 2 to 3, and the order matters. Multiplying both parts by the same number makes an equivalent ratio: 4:6 is the same green as 2:3. Ratio tables and tape diagrams show the same relationship in a picture, and they let us scale a paint mix or a lemonade recipe up or down for Field Day.