Students will learn how to add and subtract within 1,000. The concrete method is to add and subtract using base ten blocks. The pictorial method is to add and subtract using a number line. For example, when adding 184 to 655, we start at 655, then make a jump of 100 to 755, then make a jump of 80 to 835, then make a jump of 4 to 839. When subtracting, we'd jump back by the number of hundreds, then the number of tens, then the number of ones. This strategy of breaking apart one of the numbers into hundreds, tens, and ones, then making jumps, can be done without a number line as well. The usual abstract method is to add and subtract from right to left, but there is a left to right method as well. The right to left method is sometimes called the standard algorithm for addition or subtraction.

2.NBT.B.7: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.