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Introduction to the Decimal System – Cards

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A box of large number cards from 1 to 9000.
The numbers are on a white or natural wood background in decimal colors: 

1 to 9 in green  
10 to 90 in blue Twice the length of card 1 
100 to 900 in red Three times the length of card 1 
1000 to 9000 in green Four times the length of card 1 

Small empty trays.


  1. Invite the child to the lesson. 
  2. Show the child the decimal system cards box. 
  3. “These are the decimal cards.” 
  4. Ask him to bring it to a table. 
  5. Take out the 1 card and 10 card. 
  6. Ask the child to tell you what numbers those are. 
  7. Take out the 100 card and 1000 card.  
  8. “This is 100, and this is 1000.” 
  9. Ask the child how many zero’s each card has. 
  10. Proceed with a three-period lesson. 
  11. Once the child successfully identifies and differentiates the cards from one another, take the unit cards out of the box and place them on the table in a stack. 
  12. Flip over one card at a time, ask the child to name the numbers in the unit category “one, two, three, four, five, six, seven, eight, nine.” 
  13. Repeat this process for the other categories “one ten, two tens (20), three tens (30)” and so on. 
  14. “one hundred, two hundreds (200), three hundreds (300)” and so on. 
  15. “one thousand, two thousands (2000), three thousands (3000)” and so on. 
  16. Once all cards have been named, clean up. 
  17. “The cards slide easily, but that’s okay, we can carry the box carefully like this and they wont slide around as much.” 
  1. Invite the child to the lesson. 
  2. Ask the child to get a rug. 
  3. Ask the child to bring the decimal system box. 
  4. “Let’s pretend this rug is divided into four parts.” 
  5. Take out all the unit cards.  
  6. Name a few unit cards and place them randomly in the bottom left part of the rug. 
  7. Ask the child to keep naming them and placing them randomly in that same part of the rug. 
  8. Repeat this process for tens “Can you name them and place them randomly up here?” Point to the top left part of the rug.  
  9. Repeat this process for hundreds in the top right, and thousands in the bottom right. 
  10. “Can you get a math tray? I’ll be over here, but come see me and I’ll ask you to find a number and then bring it to me on the tray.” 
  11. For example, “Can you bring me the card that says 700?” 
  12. Once the child finds it, places it on the tray, and brings it to you, ask “How many zeros are in this number?” 
  13. Ask the child to place the number back on the rug, and then to come and you see you again for a new number. 
  14. Repeat this process until the child tires. 
  15. Show the child how to clean up the cards by placing the smaller numbers on top of the larger numbers, 1 on top of 2, 2 on top of 3, and so on. 


As presented.


To learn the symbols for the categories. 
To distinguish the categories by the number of zeroes.  


4 1/2


The cards reinforce what we already know about the decimal system: 
Quantities exist in sets, a set will hold no more than 9, the sets form hierarchies.
There are plastic and wooden sets.
It’s the zeroes that are important, not the colors.
It’s important to put things away, and carry the box, carefully. 
You can place a card on the tray and the child “What is this?” 

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