Currency, such as play dollars and cents, makes effective math manipulatives for adding and subtracting decimals. It also gives young learners exposure to lessons in handling and counting money. As a manipulatives activity you can pass out an equal amount of play dollars and cents to each student and then conduct addition and subtraction problems that challenge students to find the correct answers. Such an activity can be based on straightforward functions, such as $21.63 plus $0.72, or you can formulate word problems that require students to pay attention to fictional transactions.
An assortment of toy blocks in two shapes, square and rectangle, can be used to demonstrate how to add and subtract decimals. When you use blocks as manipulatives, the rectangular blocks represent the whole number one, and the square blocks -- which are half the size of the rectangular blocks -- are equal to .50 or one-half. For an activity, give each student a variety of blocks and give her addition and subtraction problems, such as adding two of the squares together or subtracting two rectangles from one square. You can also throw in a circle block that represents .25 or one-quarter.
Cookies make an exciting and edible math manipulative to use for decimal addition and subtraction. Chewy or hard cookies can be broken up or left whole to represent decimals or whole numbers. For instance, one whole cookie plus one half of a cookie equals 1.5 cookies. One whole cookie minus one quarter of a cookie equals 0.75 cookie. Allow students to eat their cookies after they are done using them as manipulatives.
Place value decimal dice are educational tools that look like dice, but instead of having dots on them like standard dice do, each face of the die is a decimal number. Students roll the dice to solve an equation. For instance, the teacher instructs the class to roll the dice and add the decimals. Then, the teacher has them roll again and subtract the lower decimal number from the higher decimal that is rolled.