A recipe is a ratio that people can taste. Double the lemons but not the sugar and the drink goes sour — and customers stop coming back. This is where a Class 6 student meets ratio as something with consequences rather than colons.
One lemon to two spoons of sugar is written 1 : 2. It does not tell you how much lemonade you are making. It tells you the relationship that has to survive whatever quantity you make.
That is the part children miss. They can compute 1 : 2 and still not see why 5 lemons needs 10 spoons rather than 6.
Making five times as much? Multiply both sides by five. The ratio 1 : 2 becomes 5 : 10, which is the same relationship at a bigger scale.
Change one side only and you have not scaled the recipe — you have invented a new and probably worse one.
The day the same shopkeeper used 18 lemons and only 24 spoons, the taste score fell to 61 and sales dropped by a third — with no change in price or weather. The ratio was the only thing that moved.
In Lemonade Empire your child runs a lemonade cart and uses this exact concept to decide what to buy and what to charge. Free, no signup, plays in a browser.
▶ Play Lemonade Empire free