The Hundreds Chart With A Twist: A Powerful Math Tool


     Most primary and many elementary teachers use a hundreds chart as a powerful tool in their math classes. It can help students master so many concepts: counting, skip counting, one-to-one correspondence, patterns, basic facts,...the list goes on. In addition, the visual and kinesthetic components of a hundreds chart are powerful tools in developing number sense.

     I've used hundreds charts for years in 5th grade.  My kids especially like the activities where I ask a question or present a problem, they put a chip on the answer, and it makes a self-checking picture at the end - much more fun than a skill worksheet.

     Several years ago, it dawned on me that the traditional hundreds chart, starting with the one (1) in the upper left-hand corner, might seem backward to some children.  It certainly did to me!  

     Starting in the upper left corner and moving down to add, or moving up to subtract is contrary to our language and our algorithms. Of course, algorithms are not our primary focus in math.  However, we often physically move down for subtraction and up for addition.  Most importantly, our language should match our math.  We say, “Add up the numbers”, “low numbers”, “one step forward, two steps back” and “count down”!   One day, I sat down and developed this chart to help my students connect what they hear with what they see and do.

     This chart starts with 1 in the lower-left corner.  It allows students to move up the board as they count higher or add.  They subtract and move down the board, more in line with algorithmic directions.  

     This “upside-down” hundreds chart is just what many of my students needed to develop number sense and see how our number system works with our algorithms!    

How to use the “Different Hundreds Chart”:

     Begin by providing a cube or game piece for students to move when finding numbers.  As students become more confident, they may move a finger to find sums or differences.

     Start with easier tasks, such as adding/subtracting tens. Here are some sample directions.

1.     Add/Subtract 10:  Call out a beginning number for everyone to mark.  Help students see that if they add 10, they will move directly up one line, a full ten spaces.  If they subtract 10, they move directly down one line.  Challenge students to add/subtract 20 or 30 and see where they land.  Try these:
         ➤Start at 50.  Add 10.  Add 20.  Subtract 10.  Add 20.  Where should we be? 90.
         ➤Start at 60.  Subtract 20.  Add 30.  Subtract 10.  Subtract 10.  Where should we be?  50

     Next, explore the patterns of adding/subtracting elevens and nines.

2.    Add/Subtract 11: Once students are confident with tens, help them discover that adding 11 moves directly up and to the right one space.  Subtracting 11 moves directly down and to the left one.  Try these:
       ➤Start at 40.  Add 11. (Students will have to move to 51.)  Add 22.  Add 11.  Subtract 22.  Add 33.  Where should we  be?  95.
       ➤Start at 35.  Add 22.  Subtract 33.  Add 11.  Add 11.  Where should we be?  46.

3.     Add/Subtract 9: Continue with 9s.  Adding  9 moves directly up one line and to the left one space.  Subtracting 9 moves directly down one line and to the right one space.   Try these:
         ➤Start at 25.  Add 9.  Add 18.  Subtract 9.  Add 27. (Students will have to move to 70.)  Subtract 9.  Where should we be?  63
         ➤Start at 46.  Subtract 9.  Subtract 9.  Add 27.  Add 9.  Where should we be?  64

4.     Now, you can challenge students to follow a series of mixed additions or subtractions and see if everyone lands on the correct number.  Try these:
          ➤Start at 45.  Add 10.  Subtract 11.  Add 20.  Add 9.  Subtract 11.  Where should we be?  62
          ➤Start at 12.  Add 30.  Add 11.  Subtract 9.  Add 11.  Where should we be?  56

     You can get this Little Different Hundred Board as a freebie right here.  

Please download, try it out, and let me know what you think.  I'd love to hear your feedback! 
Growing Grade By Grade
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