Addition and Subtraction Unit

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 Tips and Activities Teaching Addition and Subtraction:  There are many ways to teach addition and subtraction. All teachers have their own ways of doing it but here are some ideas, tips, and activities that can help you. Manipulatives: The most important thing to remember when introducing or practicing the concepts of addition and subtraction is to use manipulatives. By using manipulatives, students are able to master basic facts. Many items can be used as manipulatives, ranging from food to school supplies. Fact Family Homes: Fact families can be a difficult concept for students to understand, so here is an activity to help them master the concept.  First, I teach students that in a fact family, there are four number sentences which use only the three numbers. For example: 2,4,6 make up a fact family which looks something like this:                        2+4=6                                6-4=2                 4+2=6                                6-2=4 The students learn that the same three numbers are used throughout the fact family and that they just change spots when they go into another number sentence. After this lesson (which takes between 1-2 days, depending on age/grade level), the students then create homes for the fact families. Here is an illustration of what their fact family homes will look like: You can use milk cartons covered with construction paper to create 4 fact family homes (1 on each side). Or, students can use large sheets of construction paper to create larger homes that can be assembled to create a bulletin board. Click the picture to download a practice worksheet on fact families. Two Digit Addition/Subtraction (No regrouping): To introduce this concept, you will need to review place value, particularly the tens and ones columns.  Here is how I teach them to add/subtract two digit numbers.  First, I show them the problem on the board--   45 +23 Then I show the students that the problem has two columns, a ones column and a ten columns.  This is where I place my pre-made construction paper columns on the board and write the problem on the columns-- This helps illustrate to students to start adding/subtracting the green column (green=start) and then add/subtract the red column (red=stop).  When doing three digit addition/subtraction, the ones column is green, tens column is yellow, and the hundreds column is red.  In this way, you are utilizing traffic light signals and colors which they should already be familiar with.  Once they've become used to seeing the construction paper columns, they are able to name the columns without any problem. Two Digit Addition with Regrouping: Addition with regrouping requires the students to use manipulatives to demonstrate how they move "ten" ones over to the tens column.  Here is an example of how I begin teaching addition with regrouping. Using the construction columns (see above), students are asked to show the number 12 using only ones manipulatives and placing a ten manipulative in the tens column.  This is when the students are taught that there can be no more than 9 ones in the ones column.  Through some direct guidance, students realize they need to move ten ones over into the tens column as illustrated below--   As we practice this more I show them how this concept is incorporated into two-digit addition problems. I have found this lesson to be the best when it comes to introducing regrouping to the children. I have tried teaching regrouping without using manipulatives or showing the concept of "shifting ten over to the tens column" as we call it......and the majority of the students had a hard time learning this concept.   Two-Digit Subtraction with Regrouping: Here is a cute idea to teach kids when to "borrow" in a subtraction problem.  The name of the rule is the "BBB Rule". The BBB rules states "When the BIG number is on the BOTTOM, then you BORROW." Finger Counting: Many teachers are against students using their fingers to count.  But when students are doing the math section of a standardized test with a time limit, I want them to utilize their time efficiently.  Although I do enforce mental math with the children, there are times when they will need to quickly add/subtract.  These are some tricks that I've taught the students: 1. Adding: When adding 6 + 4, students must ask themselves "Open or closed?" With addition it is open. They open their hands and raise up four fingers (the smallest number). The palm of their hand says "6" and then they continue counting on the four fingers to get the sum. 2. Subtracting: When subtracting 15 - 8, students must ask themselves "Open or closed?" With subtraction it is closed. The put their hand in a fist and their palms will say the smallest number ("8").  They will count up to the higher number, which is 15. When they reach 15, they count how many fingers are standing to get their answer.

 Learning Centers Dice Game: (Materials: pencil, two dice, paper) This game needs at least two players. Each student takes turns to roll the dice.  The player adds/subtracts the numbers on the dice. For example, if they roll a 3 and a 5, then they say 3 + 5 = 8. The player gets a point if the answer is correct. The player with the most points wins. Card Game: (Materials: deck of cards, pencil, and paper) Similar to the dice game except that a deck of cards is used.  Fill it, Add it, Subtract it: (Materials: worksheet, index cards numbered 1-9 or playing cards, counters, pencils) Download the worksheets for this center.  Students select cards and write the numbers in the empty boxes.  When all the spaces have been filled, students will either add or subtract.  Click on the worksheets to download Domino Addition/Subtraction: (Materials: Dominoes, pencils, paper) Show students how to use dominoes to form addition/subtraction problems. Have them add/subtract the dots on two or more dominoes. Students write their number sentences on a sheet of paper.  Fact Family Homes: Create several homes from construction paper.  On the roof, write the three numbers of the fact family.  Then, on the main part of the house, add lines for the four number sentences. Laminate and place in a box, basket, or on a bulletin board.  Students use dry erase markers to fill in the number sentences on the blank lines. When they are done, they wipe the answers off with an eraser or paper towel.

Teacher Resources

 Resources Gold Mine Subtraction Game Addition Robbery Michele's Math Addition Tips Michele's Subtraction Tips Subtracting 2-Digit Numbers Mini-Lesson Subtraction Action Addition and Subtraction Game Lesson Plan Math Steps: Addition and Subtraction Facts to 20--What is it? Addition and Subtraction Idea Bank Who Has More or Less: Addition/Subtraction Game Lesson Plan 