20 Things to Do with a Hundred Chart

[Photo by geishaboy500.]

Are you looking for creative ways to help your children study math? Even without a workbook or teacher’s manual, your kids can learn a lot about numbers. Just spend an afternoon playing around with a hundred chart (also called a hundred board).

Here are a few ideas to get you started…

Addition and Subtraction

(1) Use the hundred chart as a number line to do addition and subtraction beyond what your child normally can handle. Take turns making up problems for each other to solve. Develop mental math skills by showing how to add or subtract the tens first (counting up or down) then the ones (counting left or right.)

(2) Look for addition and subtraction patterns. 3+9=? Now go to 23+9, 33+9, 63+9. What do you notice? What do 15-7, 25-7, 45-7, etc. have in common? Find other patterns.

(3) Count by whatever number you want, but start at an unusual place. Count by 5, starting at 18. Or count by 2, but start with 37. Or for a tougher challenge, practice your mental subtraction skills: count down by the number of your choice.

Number and Pattern Activities

(4) Make picture puzzles: You give the clues — either a description of a number (“It’s two less than 26″) or an equation that equals that number — and your student colors in the appropriate square. Repeat to make a design (samples here). Now, let your student make up a puzzle for you to color.

(5) From Mathwire: Cut up a hundred board into irregular pieces to make a puzzle. For more of a challenge, cut a blank chart into puzzle pieces, writing in one or two numbers per piece. Can your student fill in the rest of the numbers? [Or use this printable puzzle worksheet.]

(6) Make a hundred chart pattern (pdf) with your name.

(7) Play “Arrow Games”: Starting at the number given, each arrow means to move one square in the direction shown. What number is “45 ← ← ↑ → ↑”? How would you use arrows to say, “Start and 27 and move to 59″? Make up your own arrow code for someone to follow. Mathwire has a pdf version of this activity.

(8 ) Try Money Activities on a Hundred Chart (doc). Count by dimes or by quarters, or use the chart to make change for a dollar.

Hundred Chart Games

(9) Play “Race to 100.″ Take turns rolling one or two dice and moving that many spaces on the hundreds chart. If you correctly predict your landing place before you move (without counting squares!), then you can go one extra space as a bonus. The first person to reach or pass 100 wins the game.

(10) Play a number bonds game. Take turns pointing to any number. The other player has to say how many more it takes to make 100.

(11) Check out Hundred Chart Nim.

(12) Or try Euclid’s Game on a Hundred Chart.

Multiplication and Factors

(13) Look for counting-by (multiplication) patterns. Colored disks are nice for this, or use pinto beans. Mark the numbers you hit when you count by 2. What pattern do they make? Make the counting-by-3 pattern, or mark the 7s, etc. You may want to print several charts so you can color in the patterns and compare them. Why does the counting-by-5 pattern go down the way it does? Why do the 9’s move diagonally across the chart?

(14) Look for factors: Mark the multiplication patterns by putting colored dots along one edge or corner of each square. (That is, all the multiples of 2 get a yellow dot, for instance, and the multiples of 3 get green dots…) Which numbers have the most dots—that is, have the most factors? Which numbers have just one dot? Which don’t have any?

(15) Make the Sieve of Eratosthenes to find prime numbers. On a printed chart, blacken the box for the number 1, which is neither prime nor composite. Circle the next unmarked number (2), and then cross out all of its multiples—that is, count by 2’s and cross out every number you land on, except for 2 itself. Circle the next unmarked number (3), and then cross out all of its multiples. Keep going until every number is either circled (prime) or crossed out (composite).

(15.5) Go read the multitude of jokes about how “All odd numbers are prime.”

Fractions and Decimals

(16) What number is 1/2 of 100? How do you know? What number is 3/4 of 100? Are you sure? How can you show it is true? (What does the fraction 3/4 mean? What does any fraction mean?) What other fractions of 100 can you find? 1/10? 2/5? Can you find a number that is 1/3 of 100?

(17) The hundred chart can help you convert between fractions, decimals, and percents. Do you see how? “Percent” means “out of 100.” So 30% means “30 out of 100″—which is how much of the whole chart? If we say that the chart is one whole unit, then how much is each row (in decimal notation)? What size is each box? Can you color 0.47 of the chart? What decimal would mean the same as 1/5 of the chart? And what percent of the chart would that be?

Logic and Strategy

(18 ) A Cross pattern is a square plus the four squares directly up, down, left, and right from it. An X pattern is a square plus the four touching it diagonally. Choose any square that is not on an edge of the hundred board. Find its Cross and X patterns, and add up their sums. Can you explain why they add up to the same number? Can you find any other patterns that work that way? [Hint: Think symmetry.] Can you figure out how to predict the Cross or X pattern sum for any number?

(18.5) Find the Cross and X patterns for a date on this month’s calendar. How are these the same as on a hundred board? How are they different?

(19) Try these number logic puzzles (pdfs) from Mathwire. Then make up some puzzles of your own.

(20) Play Gomoku, also known as Five-in-a-Row, on a printed hundred chart. Use a wide-tip marker to make Xs and Os, or use pennies and nickels to mark the squares. On each turn, the player must make up an equation that equals the number in the square he wants to mark.

(20.5) If you enjoy Gomoku, you can download a freeware version here. But it doesn’t come with a hundred chart.

Edited to Add

Can you think of anything else to do with a hundred chart? Add your ideas in the Comments section below, and I’ll post the best ones here:

(21) The Factors & Multiples game: The first player marks any number on the hundred board. His opponent marks a factor or multiple of that number. Players alternate, each time marking a factor or multiple of the last number played. The player who marks the last number, leaving his opponent with no move, wins the game.

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This post is a revision and update of my original post, 7 Things to Do with a Hundred Chart, and is part of my Hundred Board Series.

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Have more fun on Let’s Play Math! blog:

• Free Multiplication Bingo Game
• Math Game: What Number Am I?
• Negative Numbers for Young Students
• Math Facts Are Like Learning To Type
• Pre-Algebra Problem Solving: The Tools