Understand a ratio as a comparison of two quantities, write it in the forms a to b, a:b, and a/b, and build a ratio table.
A ratio compares two amounts. If a recipe uses 2 cups of flour for every 3 cups of milk, the ratio of flour to milk is 2 to 3. You can write that three ways: 2 to 3, 2:3, or 2/3 - all three mean the same comparison.
Order matters in a ratio. "Flour to milk" (2:3) is not the same as "milk to flour" (3:2). Always check which amount is named first before you write anything down.
A ratio table lists pairs of numbers that keep the same relationship as they grow together. If 2:3 is doubled, you get 4:6 - still the same comparison, just a bigger batch.
Mastery looks like: They write a ratio in the correct order from a word description and extend a ratio table by multiplying both numbers by the same amount.
Common stumbles: Reversing the order of the two quantities; adding the same number to both parts instead of multiplying by the same factor.