A base is a way for you to express numbers using place value. The standard for counting numbers is base 10, which means that every whole number has a value that is 10 times greater than the number to its right. For example, in the number 11, the one on the left represents a 10, which is 10 times greater than the one on the right. Base 10 blocks are a manipulative tool that helps teach the concept of base 10 numbers to early elementary students. These blocks also help teach the concepts of addition and subtraction to beginning mathematics students.
Things You'll Need
 Base 10 Blocks with hundred flats, 10 rods and single units

Learn place value. Introduce a unit to your students. A unit is one cube and is used to represent the ones place value. Stack 10 units and show how they are equal to one rod. Teach your students that a rod represents the tens place value. Finally, place 10 rods side by side and show how they equal one flat. Teach your students that a flat represents the hundreds place value. Practice reviewing these concepts until your students understand how units, rods and flats are related to each other.

Practice reading and writing numbers. Write examples of single, double and tripledigit numbers on the board. Using base 10 blocks, have your students represent the numbers on the board. Have your students practice reading numbers by arranging base 10 blocks to represent a single, double or tripledigit number and having them read the represented number aloud.

Model addition by using base 10 blocks. Give students a number they must represent using their base 10 blocks, such as 16. Have your students use only units (ones cubes) to represent their numbers. Then give them a second number to represent using their blocks, such as 12. Have them combine the two groups of units into one group to create a sum. Reinforce the idea that when you combine two or more groups of units you are adding and the end result is the sum.

Demonstrate subtraction. Assign students a number to represent with their blocks. For example, have your students represent the number 23, using only units. Ask them to take away a set number of units from 23. For example, have your students take away seven units from 23. Tell your students that when they take away units they are subtracting to find a difference. For example, 23 take away seven is a difference of 16. As your students progress, have them use rods and units to subtract, showing them how to "borrow" 10 units to replace one rod.
References
 PurpleMath.com; Number Bases
 "Everyday Mathematics Student Reference Book: Grade One"; The University of Chicago School Mathematics Project; 2007
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