A recipe says what you get for what. An arrow is such a recipe: 1 🌳 ──▶ 4 🪵 means "1 tree turns into 4 planks".
Several arrows in a row form a chain. If 2 🪵 ──▶ 1 🪑 follows, then every 2 planks turn into 1 chair.
If the frame is on the left, you know the supply: 6 trees give 6 · 4 = 24 planks, and 24 planks give 12 chairs.
If the frame is on the right, you know the goal and work backwards: for 12 chairs you need 24 planks, and for those 6 trees.
Write into every gray box the amount that arrives there - the boxes in the middle too. They are your working.
Example
For parents
What does this exercise practice?
Going forwards, the chain is repeated multiplication. Going backwards, it is the opposite: needing 2 planks for 1 chair means dividing - without the word having to come up. And because several steps follow one another, the child plans instead of just calculating: it first has to see which step comes first.
Common pitfalls
The most common mistake is skipping a step and writing the number straight at the end. It helps to keep a finger on the arrow and really write down every number in between. Going backwards, multiplying turns into dividing - many children first carry on in the wrong direction there.
How to practice at home
Cook a recipe for double the amount: if 4 eggs are enough for one cake, how many do you need for three? And backwards: you have 12 eggs - how many cakes is that? The same works with building blocks ("3 blocks make one wall") or returnable bottles.
Related: Times as a dot array, Which Is Better?