Here is a pancake recipe that feeds four people: 2 eggs, 400 g of flour and 600 ml of milk. Tonight, eight people are coming for pancakes.

How would you change the recipe so everyone gets the same-sized pancakes? What has to happen to every ingredient?

Below are four recipes drawn as ratio bars: the longer the bar, the bigger that ingredient's share. For each one, say what the bars are showing you and how the amounts relate to each other, and we will agree it as a class before moving on.

Today we'll build this on the ratio bars together. Here is a new smoothie: 1 part banana to 5 parts milk, poured into a 900 ml jug for a group. Before we reveal it, tell me how many equal parts share the 900 ml and what one part is worth. Then we'll set the bars and read off each actual amount.

Today we'll work through three mixtures together, each one a little harder than the last. Tell me how many parts share the total before we reveal each one.

• Make a 1:2 lemon-and-water drink in a 900 ml jug.
• Make 700 g of a nut-and-raisin mix. It starts as 250 g nuts to 100 g raisins — divide both by 50 to get 5 parts nuts to 2 parts raisins.
• Make a 2:3 blue-to-white paint mix in 2500 ml.