In a previous article, I showed you how to teach your child how to count from 1 to 9 and then from 10 to19. With this new article, you will know how to teach him how to count from 20 to 99.
As I explained many times before, you must always teach the first notions in a concrete way. Then you can show him the symbols that represent the abstract part. Last, you can associate the concrete part to the abstract one.
For the concrete part, we use a box of tens – beads of pearls.
With the lesson in three steps, teach: « 20, 30, 40 ».
Take two tens and say: « this is 20, 2 tens are 20 ».
Take three tens and say: « this is 30, 3 tens are 30 ».
Take four tens and say: « this is 40, 4 tens are 40 ».
For the second step of this lesson, set in front of the child (on a small rug) the 2 tens for 20, the 3 tens for 30, and the 4 tens for 40 and ask him: “show me 20”, “show me 30”, then “show me 40”. If he responds correctly, set the groups of tens aside and ask the same questions.
During the second step of this lesson, you can set all the tens in front of the child and ask him: « now with these tens, make 20 », « then make 30 », and last « make 40 ». If the child answers correctly and stays concentrated, you can go on to the third step of the lesson.
Take four tens together, set them in front of the child and ask: “what is it?”. Then take them back, put two tens together and ask: “what is it?” and last, take away those two tens and set three in front of the child and ask the same question.
As a conclusion, tell your child while setting the tens in front of him on the rug: “today, we have learned that two tens are 20, that three tens are 30, that four tens are 40”.
To continue this teaching, you can choose between these two options considering your child’s reactions.
1) Continue to teach him the numbers 50, 60, … until 90 using the preceding example.
2) Teach him the symbols that correspond to the quantities that he already knows (even if he does not know all the numbers to 99).
You will notice that numbers «70» and «90» are hard for the child to master. So to avoid failure, you can teach him the symbols of the numbers 20, 30, 40, 50, 60 which are easier to learn and then go on to the concrete part which corresponds to 70, 80 and 90.
In a Montessori class, to teach the symbols to the quantities which correspond to 20, 30 and 40, we use what we call a “second Seguin table” (see photo).
We set this table in front of the child along with the beads of the numbers from 1 to 9. We show him the first box and ask him if he remembers what the number is.
We show him the symbol corresponding to 20 and say: « this is 20 », then the symbol for 30 and say: « this is 30 », and then the symbol for 40 and say: « this is 40 ».
Then, we go on to the second step and ask him to show us “20”, then “30” and last “40”. We repeat this exercise a number of times.
We go on to the third step of the lesson. We show him number “30” and ask “what is it?”. Then, we show him number “40” and ask “what is it?” and so on…
As a conclusion, we tell him: today, we have learned «20», «30» and «40». We tell him while showing him the numbers.
As soon as your child knows the quantities 20, 30 and 40 with their corresponding symbols, you can teach him the association between concrete and abstract. Set the Seguin table in front of the child along with the beads of pearls for tens, and ask him to make a small pyramid with the colored beads.
You can also decide, just like for the concrete notion of these numbers, to teach the symbols until 90, but in my experience, children often lose their interest because the process is a long one.
For the association between concrete and abstract, show the child how to proceed and then he can do it on his own because he already knows everything.
You can set two tens in front of number 20 of the Seguin table. Do the same with three tens and invite the child to pursue the exercise.
Then you can take from the beads pyramid, the little red pearl which corresponds to “1” that you set in front of the two tens, and while showing the child say: “21”. Then, take the beads for “4” and set it in front of the four tens and say “44”. Go on that way with all the numbers that he knows.
Proceed the same way to number 99. Do not worry if your child takes more time to memorize numbers from 71 to 79 and from 91 to 99. It is not easy at all!
Then, we have material on paper that we use to complete these lessons. Exercises are needed to extend the child’s knowledge.
It is quite important to find different ways to teach the same concept so that the child does not get bored. Do not forget that all children are different, some are more interested in sound, some are more visual…