Thinking Addition Means "Join Together" and Subtraction Means "Take Away"

Ø  A common error students make when solving word problems is to distinguish addition and subtraction. Often they confuse the operations when the word more is used and sometimes think that take away means to remove instead of finding the difference.

 

Ideas for Instruction

v The teacher needs to ensure that they use the words plus and add when reverring to the addition symbol and minus and subtract when referring to subtraction symbol. Reinforce this when students read their equations.

v Give students many opportunities to take apart a set of objects and put it back together again, perhaps using Unifix cubes, Cuisenaire Rods or bicolored counters.

v Provide students with activities that five them the opportunity to see that quantities can be represented in many different ways.

§  Give students two colors of cubes and ask them to represent a number in different ways. (For example, 6 = 1+5, 2+4, 3+3)

§  Students can arrange a specific number of cube tiles on a twenty-five square grid in different ways.

§  Have prekindergarten students sort a limited set of dominoes in order to explore various ways of representing a specific amount.

v Students can solve simple context – related story problems, using Daily calendar routines.  You can ask, “Today is Tuesday, September 11.  How many more days until it’s the 15^th?” Or “We’ve been in school for 97 days; how many days until the 100^th day?”

v Incorporate story problems when reading picture books.  How Many Snails? (1994), by Paul Giganti, has pictures on each page that students can use to practice counting, naming attributes, determining part-whole relationships, and performing comparative stubtraction.  You can ask questions like, “How many clouds do you see?  How many clouds are gray?  How many clouds are white?  How many clouds are small?  How many clouds are large?”

Home

Counting with Word Numbers

Renaming and Regrouping when Adding and Subtracting Two - Digit Numbers

Misapplying Addition and Subtraction Strategies to Multiplication and Division

Multiplying Two - Digit Factors by Two - Digit Factor

Understanding the Division Algorithm

Understanding Fractions

Adding and Subtracting Fractions

Representing, Ordering and Adding/ Subtracting Decimals