We realize we don’t know the numbers from 0 to 20 and decide to write them at home (in numbers and in letters). Clara has written them on some cards and since we think it’s a very good idea to practice them, we decide that everyone can create their own number cards.
We want to make them with cardboard. First we count how many numbers we have to write and how many numbers we can write in one cardboard. Then we think how many pieces of cardboard we need.
Once we have calculated the number of cardboards we need, everyone makes their own number cards.