Using Manipulatives to Teach Decimals

Manipulatives are games and hands-on activities that get the student’s senses involved in the learning process. Ideally, manipulatives will aid in the learning process for auditory, visual and rote learners. Students are able to listen, look, repeat, and actively participate in the learning process.

Decimals do not have to be difficult to learn. Students often do not realize that decimals are part of most currency systems, so they are actually seen and used every day. The following manipulatives can help make the decimal process much easier for everyone:

• Use money to show students basic decimals. The Euro, Canadian dollar and U.S. dollar are all equal to 100 cents. If the dollar or Euro equals one whole, then a ten-cent coin is equal to one-tenth. A one-cent coin is 1/100th. Students can grasp the basic decimal place values by thinking in terms of monetary values. Money also makes the decimals real, instead of just a concept. Some students find it easier to learn math concepts if there is a real-world use for them.
  
  
• Use grid (graph) paper to help students visualize the place values. Have students draw a box that is 10 squares long and 10 squares high. The box is one whole, and each row or column is one-tenth. Each box, then, represents the hundredth place.
  • Have students color in boxes to represent different amounts. For example, they can color in 3 blocks to see what 0.03 looks like.
  • Coloring in the boxes can help students understand addition with decimals. For example, if they are trying to answer 0.02 + 0.05, they can color in 2 boxes, and then color in 5 boxes. When they count the number of boxes, they will get 7 hundredths as their answer.
  • This can also be used to teach multiplication. For example, if the problem is 0.2 x 0.8, the students can use the blocks to see the answer. The problem is in tenths, which is a whole row or column. Have the students color 2 rows in blue. Then have them color 8 columns in red. The number of blocks where the colors overlap, or the number of purple blocks, will be the answer to the problem. In this case, it will be 16 blocks. The students have been taught that one block is equal to 0.01, so 16 blocks would be equal to 0.16.

• Use blocks and a balance to demonstrate place values. Mark a number “1” on the balance. Have blocks labeled 10, 100, 1000, 0.1, 0.01, and 0.001. Place the 10 block on the balance scale in front of the 1. The balance will tip to that side. Explain that it takes 10 ones to make that block. Then put the 0.1 block on the other side, which will level the scale. Explain that the 1 has ten of those blocks. Do not emphasize weight or equality with this exercise. Emphasize the value of ten because that is the base of the decimal system. This lets the students see the number change on each side of the central 1.