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- 1. Addition & Subtraction Basic Facts Salem Keizer Public Schools Curriculum, Instruction & Assessment Strategy Development © May 2007 & Practice Handbook What’s Inside: Strategic Development of Basic Facts Suggested Practice When students first learn to practice after thinking Timeline for Grades 1-3 2-3 add, they move from need- strategies have been devel- ing to count all objects to oped. In order to reach this Mini-Lessons, being able to start with one goal, two critical elements Discussions, and number and count on. This are needed for effective Activities for Practice: 4-7 is an important step in the fact practice: development development of addition of efficient strategies; and By focusing on strategies, and subtraction strategies. practice of facts in an order students can build new Appendix : The next step is the devel- that helps to build efficient strategies based upon opment of thinking strate- strategies. Strings 8 facts that they already gies. Unfortunately, the Prior to practice, it is criti- know. Rather than teach Strategy Cards 9 traditional practice of cal to incorporate mini- facts successively from timed drill encourages stu- lessons that deal specifi- +0 through +9, a more Around the Class 10 dents to use counting cally with strategy devel- effective strategy order is: strategies and does nothing Beat the Calculator 10 opment. While Bridges think one (two) more/ to promote thinking strate- includes many lessons on less; combinations of ten; gies. Because of this, we Interval Training 11 strategy development and add ten to a single digit see many upper elementary practice, additional mini- number; doubles; students relying on count- lesson ideas are included in neighbors; make a ten; ing to solve basic addition this handbook for interme- sharing; think addition; and subtraction facts. diate teachers and for 1-2 building up/backing down The goal for basic fact teachers who want to in- through ten. See pages 4- practice should be auto- clude additional practice. 7 for more information on In order to become maticity gained through these strategies. fluent with basic ad- dition and subtrac- tion facts, students When To Practice need: Strategy development and your math program. Addi- Except for Bridges Lessons • A solid understanding of practice for basic facts will tional practice (or practice specifically devoted to the concepts of addition be most effective if it hap- in intermediate grades) can strategy development it is and subtraction. pens 2-3 times per week be done as a warm-up at not best practice to devote for 5-10 minutes. For 1st the beginning of math time a whole class period to ad- • Opportunities to develop and 2nd grades, Bridges or for 5-10 minutes at some ditional practice. Short, efficient strategies for includes strategy develop- other time during the day. frequent mini-lessons will knowing facts. ment and practice in Num- Several of the practice ac- be much more effective. • Opportunities to practice ber Corner as well as in tivities can be incorporated Fact practice is also an ex- Lessons, so it is critical to cellent homework assign- using those strategies. into transition times or include Number Corner in used as “sponge” activities. ment.
- 2. Grade 1 September Suggested Timeline for Strategy Development and Practice Addition Fact Strategies: October ♦ Share and Practice Strategies ⇒ Counting All for Addition ⇒ Counting On for Addition ⇒ Think Add Zero: 4+0 8+0 November What About Fact Prac- Addition/Subtraction Fact Strategies tice in Kindergarten? ♦ Share and Practice Strategies The focus of kindergarten is to ⇒ Counting On for Addition December develop number concepts and a ⇒ Counting Back for Subtraction basic understanding of the con- ⇒ Think Add/Subtract Zero: 4+0 8+0 7-0 2-0 cepts of addition and subtraction. Kindergarten students spend a lot of time developing counting skills and understanding of num- Addition/Subtraction Fact Strategies January bers and how they relate to one ♦ Share and Practice Strategies another. Time spent developing a good number foundation will ⇒ Continue practicing strategies listed in October-December as needed benefit students when they begin to develop and practice strategies ⇒ Addition Doubles (1 thru 5 and 10): 1+1 2+2 3+3 4+4 in first grade. 5+5 10+10 February ⇒ Think One More/Less: 5+1 or 8-1 ⇒ Add Ten to any Single Digit Number: 3+10 10+7 Why not just count on? Counting on is a widely promoted strategy. While it is an important step in the development of strate- March gies, it is equally important that students move beyond counting strategies. When adding one, two Addition/Subtraction Fact Strategies or three, counting on is efficient because it is easy to keep track of ♦ Share and Practice Strategies how many have been added on. ⇒ Continue practicing strategies listed in October-February April However, students often apply as needed this strategy to facts where it is ⇒ Combinations of Ten: : 9+1 4+6 8+2 or not efficient, such as 6+8. For 6+?=10 ?+3=10 8+?=10 this reason, counting-on should be ⇒ Relate Addition to Subtraction: For 6-3 think 3 + 3 = 6 so downplayed beyond first grade. 6- 3=3 May-June Even with simple facts like add- ing two, encourage students to “think two more” rather than count on. Page 2 Addition & Subtraction
- 3. Grade 2 Grade 3 Addition/Subtraction Fact Strategies: Addition/Subtraction Fact Strategy Development and September ♦ Share and Practice Strategies Practice: ⇒ Counting On for Addition ♦ Share and Practice Strategies ⇒ Counting Back for Subtraction ⇒ Think One/Two More/Less: 5+1 7+2 or 8-2 4-1 ⇒ Add/Subtract Zero: 8+0 3-0 ⇒ Combinations of Ten: 9+1 4+6 8+2 or ⇒ Think One More/Less: 5+1 or 8-1 6+?=10 ?+3=10 8+?=10 October ⇒ Combinations of Ten: 4+6 8+2 or ⇒ Doubles: 3+3 7+7 4+4 6+6 6+?=10 ?+3=10 ⇒ Neighbors: 3+4 7+8 4+5 6+7 ⇒ Addition Doubles (all): 3+3 7+7 4+4 6+6 ⇒ Breaking Apart/Sharing: 6+8 = 6+6+2 (break 8 into 6+2) or Addition/Subtraction Fact Strategies: November 7+5 = 6+6 (share one from the 7—give to the 5) ♦ Share and Practice Strategies ⇒ Make a Ten: 5+9 = 4+10 or 8+6 = 10 + 4 ⇒ Continue practicing strategies listed in September/ October as needed ⇒ Think Addition: 15-8=? Think 8+?=15 ⇒ Addition Doubles and Neighbors: 3+3 3+4 ⇒ Building Up/Backing Down Through Ten: 7+7 7+8 4+4 4+5 17-9=? Think if I start at 9, I need 1 more to get to December ⇒ Relate Addition to Subtraction 10; then 7 more to get to 17; 1+7=8 so 17-9=8 ⇒ Add Ten to any Single Digit Number: 3+10 10+7 15-7=? Think 15-5=10; I need to subtract 2 more because 5+2=7 so 15-7=8 ♦ Adding/Subtracting Multiples of 10 Addition/Subtraction Fact Strategies: ♦ Doubling and Halving January ♦ Share and Practice Strategies ⇒ Continue practicing strategies listed in September-December as needed Some Thoughts about Subtraction ⇒ Think Two More/Less: 9+2 2+7 8-2 6-2 It is important for students to know that not all sub- ⇒ Subtraction Neighbors: 7-6 9-8 6-5 traction is take away. While “take away” is a com- February ⇒ Add/Subtract Ten: 10+7 8+10 13-10 16-10 mon way of thinking about subtraction, the difference model is a powerful model of subtraction. The differ- ence model of subtraction is how we compare things like quantities, distances, heights and weights. When students only think subtraction as “take away” they often rely upon counting back for all subtraction in- March stead of using thinking strategies. Thinking of sub- traction as the difference between two numbers en- ables students to be more flexible with strategies. Addition/Subtraction Fact Strategies: ♦ Share and Practice Strategies What About +/- Fact Practice for ⇒ Continue practicing strategies listed in April September-March as needed Older Students? ⇒ Add/Subtract Ten and Nine: 10+5 9+5 Many older students who have difficulty with facts 10+4 9+4 17-10 17-9 16-10 16-9 use counting as their primary strategy. Examine what number relationships the student has. Without a solid ⇒ Doubles and Halves understanding of numbers and their relationships May-June ⇒ Think Addition for Subtraction thinking strategies are very difficult. Use mini les- sons to develop number concepts and relationships that will prepare students to use thinking strategies that are discussed in the following pages. Strategy Development and Practice Page 3
- 4. Add/Subtract Zero, Think One More/Less, Think Two More/Less Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Discussion of Adding or Subtracting 0, 1 or 2 ♦ Around the Class (see p. 10) ⇒ Have students solve word problems that in- volve adding or subtracting 0, 1 or 2. Draw ⇒ Add or Subtract 0, 1 or 2 pictures to go with the story. Have students ♦ Interval Training (see p. 11) share their thinking. ⇒ Zeros, Ones, Twos and Mixed ♦ +/- 0, 1 or 2 using a ten frame ♦ Grade 1 & 2 Number Corner Activities: ⇒ Display a Ten Frame and ask students what would be 0,1, or 2 more or less. Show on the ⇒ Gr 1, Feb. Thurs. Thinking 3 & 4: One More, One Less/ ten frame. Two More, Two Less NC TG p. 289-292 Think two more ⇒ Gr 2 , Jan.-Feb. Workout Wheel NC TG p. 152-155 Combinations of Ten Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Make Ten on the Ten Frame or Ten Strip ♦ Around the Class (see p. 10) ⇒ Display a partially filled ten frame card. Ask students how many more are needed to make ⇒ How many do I need to get to ten? ten. Say and record the equation. If a student says 6 the class says 6 + 4 = 10 3 +___= 10 ♦ Interval Training (see p. 11) ⇒ Make 10 ♦ Grade 1 Number Corner Activity _____ + _____= 10 The students record the number ⇒ Two to Make Ten NC TG p. 328-329 they hear in the first blank and fill in the second blank with what they need to make 10. ♦ Make Ten without a Ten Frame ⇒ For students who need a challenge: ⇒ Display a blank Ten Frame. Say a number less • Make another target number, such as 11 or 12. than ten. Students start with that number and say and record how many are needed to make ten. ♦ Make Ten Go Fish: use ten frame cards The ability to get to ten from any single digit number is critical. Many ⇒ The goal is to make ten. If you have a 7 you would ask thinking strategies that are used with larger numbers are dependent upon one of the other players for a three. this skill. Spending time on developing this concept is time well spent. Add/Subtract Ten Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Ten Frame Cards, Arithmetic Rack ♦ Around the Class (see p. 10) ⇒ Use Ten Frame cards to model adding or subtract- ⇒ Add or Subtract 10 ing ten. Ten frame cards or an ♦ Strategy Cards (see p. 9)) Arithmetic Rack can ♦ Interval Training (see p. 11) be used to show 10 + 6 and 16-6 ⇒ Add 10 ♦ Grade 1 Number Corner Activity ♦ Grade 1 Number Corner Activities ⇒ Gr1 Ten & More a Match Game NC TG p. 53-54 ⇒ Gr1 Ten & More NC TG p. 51-57 ⇒ Gr 1 Unifix Cube Ten & More NC TG p. 114-115 Page 4 Addition & Subtraction
- 5. Doubles Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Reflecting Doubles ♦ Around the Class (see p. 10) ⇒ In pairs, one student holds up 1 to 10 fingers. The part- ⇒ Doubles Around the Class ner mirrors the same number of fingers, touching them to their partner’s fingers. Emphasize that two touching ♦ Beat the Calculator (see p. 10) hands (5+5) will always be ten. ⇒ Doubles ⇒ Say (or say and record) the doubles ♦ Interval Training (see p. 11) equation that is being modeled. ⇒ Doubles (___ + ___) ⇒ For students who need a challenge: ♦ Discussion of Double Images • Double and Double Again ⇒ Discuss images and draw pictures to illustrate the dou- bles • Double, Double Again and Double One More Time 6+6= ♦ Strategy Cards (see p. 9) ⇒ Double Images ♦ Ten Strip, Ten Frame, or Arithmetic Rack Doubles ♦ Double Dice ⇒ Put two like Ten Frame cards or Ten Strips on the over- head or white board and discuss. Write the equation. ⇒ Roll a die, double it and record the equation i.e. Roll a 6 and record 6+6 = 12 Neighbors (Doubles Plus One) Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Discussion of the connection between Doubles and ♦ Around the Class (see p. 10) Neighbors Using Visuals ⇒ Double it and add one ♦ Ten Frame Cards ♦ Strategy Cards (see p. 9)) ♦ Ten Strips ♦ Interval Training (see p. 11) ♦ Arithmetic Racks ⇒ Double then Neighbor ♦ Double Dice Plus One ⇒ Roll a single die with numerals or dots then say and record the complete double-plus-one fact. If a 6 is ♦ Strings: Doubles and Neighbors (see p. 8) rolled, the student says and records 6+7=13. ⇒ Some strings to use: ♦ Grade 1 & 2 Number Corner Activities for Dou- 4+4 5+5 3+3 bles and Neighbors 4+5 5+6 4+3 ⇒ Gr 1 Seeing Doubles & Neighbors NC TG p. 101-104 and p. 239-241 6+6 6+5 8+8 6+7 6+6 9+8 ⇒ Gr 1 Doubles & Neighbors NC TG p. 372-375 7+6 8+9 ⇒ Gr 2 Workout Wheel NC TG p. 152-155 In order to use the thinking strategy of neighbors students must know the doubles facts and be able to think one more. Strategy Development and Practice Page 5
- 6. Halves Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities ♦ Discussion of Doubles and the relationship to ♦ Strategy Cards (see p. 9) Halves front back or inside ⇒ Use Ten Strips, Ten Frames, or Arithmetic Rack to provide a visual model for doubles. Then have stu- dents come up with the related subtraction fact (the half fact). ⇒ You can also use reflecting doubles with fingers to provide a visual model of doubles and then relate them to halves. Think 7+7=14 Half of 14 is 7 7 + __ = 14 14-7 = 7 ♦ Strings: Doubles and Halves ♦ Around the Class (see p. 10) ⇒ Some strings to use: ⇒ Halves Around the Class (even numbers) 4+4 6+6 8+8 ♦ Interval Training (see p. 11) 8-4 12-6 16-8 ⇒ Halves. Students can half the number (÷ 2). You may want to say the numbers rather than using a CD so that you can 5+5 7+7 9+9 choose only even numbers. 10-5 14-7 ___-9 ♦ Grade 2 Number Corner Activity to Practice this strategy: ⇒ Grade 2 Jan –Feb Workout Wheel NC TG p 152-155 Make a Ten (Fast Nines) Mini-Lessons and Discussions Activities for Practice for Developing Strategies *see appendix for information on these activities Make a Ten is one type of sharing strategy. In Make a Ten you ♦ Strategy Cards (see p. 9) break one addend apart to make the other addend ten. ♦ Discussion of making a ten to help with adding a 9 or 8 front back or inside This strategy involves building onto the 8 or 9 to make a ten and then adding on the rest. ⇒ Use Ten Frames or Ten Strips to model a fact such as 8 + 5. Show 8 on one ten frame and 5 on another ten frame using counters or cubes. Then decide an easy way to show the answer without counting. Model moving two counters from the 5 to make the 8 become 10. Then your ten frames show 10+3. Discuss how this is the same as 8+5. Give stu- dents two blank ten frames and some counters and have them do this strategy with another problem such as: 8+4, 8+6, 9+4, 9+5, 9+6, 9+7 ♦ Around the Class (see p. 10) ⇒ +9 or +8 around the class ♦ Interval Training (see p. 11) 9+6 becomes 10 + 5 ⇒ +9 or +8 In order to use this strategy students must be able to think of numbers 11-19 as ten and some more. Page 6 Addition & Subtraction
- 7. Sharing Mini-Lessons and Discussions Activities for Practice for Developing Strategies *See appendix for information on these activities Sharing involves breaking one or more of the numbers apart in order to create an easier problem. Make a ten is one type of ♦ Strategy Cards (see p. 9) sharing that is commonly used when one of the addends is 8 or 9. front back or inside ♦ Discussion of ways to make an equation easier by using facts they know ⇒ Put up an equation such as 6 + 8. Have students think of how to make the equa- tion easier. Represent their thinking using numbers and Think visuals. 5 + 5 and 2 more 6+8 6 + 6 + 2 Subtraction as Think Addition Mini-Lessons and Discussions Activities for Practice for Developing Strategies *See appendix for information on these activities In order for students to effectively use think addition, students ♦ Strategy Cards (see p. 9) must first master addition facts. ♦ Fact families ♦ Connect subtraction to addition ⇒ Give students a subtraction fact ⇒ On overhead count out an amount of counters. After and have them find the related counting all of them, cover the entire group. Count and addition fact. remove some from the covered group. Display those next to remaining covered counters. ⇒ Give students 3 numbers in a fact family and have them find the ∗ Example: Count and cover 12 counters. Remove addition and subtraction equations. and display 5. Have students think “5 and what makes 12”. Record the 2 equations 5 + 7 = 12 and 12-5= 7. Uncover and check. Building up/Backing Down Through 10 for Subtraction Mini-Lessons and Discussions ♦ Back down through 10 using ten frames or ten strips for Developing Strategies ⇒ Instead of building up through to ten you can This strategy is based on the difference model of subtraction. Stu- back down through ten. dents use the number 10 to help simplify finding the difference be- You are using ten as a tween two numbers. bridge as you subtract. ♦ Build up through 10 using ten frames or ten strips ♦ Building up/backing ⇒ This strategy is effective for the “hard” subtraction facts start- down through 10 using an open number line ing with teen numbers. Basically you are thinking addition, ⇒ An open number line is a great way to record the think- but using 10 as a bridge to simplify the facts. Modeling on ten ing for subtraction problems. This is a good transition frames as shown is a from using ten frames to model the strategy to having good way to visually students being able to do the strategy in their heads. show the strategy. Strategy Development and Practice Page 7
- 8. Strings One of the most effective mini-lessons for develop- an arithmetic rack, but the same ing computational strategies are strings. Strings string could be done with ten are sets of addition and/or subtraction images or strips as the model as show here. problems that are specifically chosen because they relate in such a way as to highlight number rela- In the example below the tionships. The problem sets are likely to lead to a model is used to develop the strategy for doubles discussion of specific strategies. These discussions and neighbors without formally showing an equa- should explore the relationships between the prob- tion (5+6 = ). Once students have had sufficient lems and compare the efficiency of different strate- experience focusing on the number relationships gies that are presented by students. using the model, then an equation can be added while the model is only partially used. For exam- Visual models such as ten frames, ten strips, num- ple, show an arithmetic rack or ten strips with six ber lines, or arithmetic racks can be used by the and six as a quick image and ask teacher to support students’ mathematical thinking “How much and how do you during the discussion of the string. A visual model know?” Then write the sentence can also be used to help make one child’s thinking 6+7 = and ask “How much is 6+7? How do clearer to other children. you know?” Eventually you can show just the num- ber sentence and use the arithmetic rack or ten strips Appendix The example below will help illustrate how a string of quick images (in this case 5+5, 6+6, 5+6) can be as a model of the strategies when children share used to develop the strategy of using a double to their answers. In this way, the model moves from solve a neighbor (i.e. using five plus five to solve being a support for mathematical thinking to a rep- five plus six). In the example the teacher is using resentation of mathematical thinking. T: I’ll show you some beads on the arithmetic rack for just a moment and I want you to think about how many beads you see and how you know how many there are . (Teacher uncovers the left side of the arithmetic rack for a moment, then covers it up again). What did you see? Nina: I saw ten. There were five reds on the top and five reds on the bottom. Five plus five is ten. T: Here’s the next one. Look quick! What did you see? Jamal: This time there were six on top and six on the bottom. I knew it was six because there were five reds and one white. Six plus six is twelve. Juan: I saw that there was just one more on the top and one more on the bottom than last time. So it was ten plus two more—ten, eleven, twelve. T: Here’s another one. Marita: We already did five plus five and this is just one more than that—it’s eleven. Five plus five is ten and five plus six is eleven. Jamal: I was thinking that it is one less than what we just did. Six plus six is twelve and this is just one less—it’s eleven. Jordan: I just saw five reds and another five reds and then one white. That’s five and five is ten, plus one is eleven. Page 8 Addition & Subtraction
- 9. Strategy Cards What are Strategy Cards? Strategy cards are basic Using Strategy Cards Students should practice no fact flash cards that help students connect a specific more than about 5 strategy cards at a time and for no thinking strategy to learning that fact. Strategy cards more than 5 minutes at a time. Practice with strategy can be made using index cards. If using a 3x5 card, cards can take place individually or in pairs during the fact is written on the front of the card and the class. It is a good 2-minute warm-up prior to Interval thinking strategy for getting the answer is recorded Training or Beat the Calculator (see p. 10-11) . It also on the back of the card. Alternatively, if using a makes an excellent homework assignment. Students larger card, the card can be folded in half with the should look at the fact(s) on the front of the card. If fact written on the front and the strategy recorded they don’t remember the answer, they should look at inside the card. The answer to the fact is not written the strategy and figure out the answer. The goal is for anywhere on the card. The thinking strategy itself is enough for the stu- The answer to the fact is not written anywhere on a strategy card. dent to be able to figure out the an- The thinking strategy itself is enough for the student to be able to swer to the fact. By not having the figure out the answer to the fact. By not having the answer on the card, students must actively use the thinking strategy. answer on the card, students must actively use the thinking strategy. Below is an example of two strategy cards made by students to remember the strategy without needing to a student working on double facts. turn the card over to look at it. It will be very helpful Appendix to model this thought process out loud for your stu- front back (or inside) dents. For example, hold up the 7+7 strategy card shown at the left with the fact facing you and the strat- egy facing the students. Then say “hmm... I remember there are two sets of hands showing seven fingers each. Put the fives together to make 10 and put the twos together to make 4. So, 7+7 is 14.” Management of Strategy Cards One way to store and keep track of strategy cards is to give each student a 6x9 manila envelop. For students in second grade and older, an addition table can be glued onto the en- velope and facts that the student knows can be colored over with a dark crayon. The facts a student is cur- rently working on can be colored in a light color. In the example shown here, the student knows all of the adding zeros, ones and tens strategy facts. She also knows some addition doubles. She is working on 6+6, Making Strategy Cards Ideally, strategy cards are 7+7, 8+8, 9+9. made by students or with input from students as they Once she knows identify facts that they don’t yet know. It is impor- these facts, they can tant that students use a strategy that makes sense to be colored a darker them, so making the cards should come after mini- shade. When a stu- lessons or discussions of strategies. For example, dent is finished with after a discussion of ways to remember doubles (see a strategy card, that p. 5), students who don’t know all of their double card can be put into addition facts can make strategy cards for those facts a “doubles strategy they don’t yet know. It is fine for an adult or another cards” folder to be student to help with the drawing of the cards since we reused by another don’t want students to spend an inordinate amount of student in the future. time making the cards. Strategy Development and Practice Page 9
- 10. Around the Class In this activity, the first student will call out a num- vide a scaffold for students who need it. For ex- ber, give a three second “think time” signal and then ample, if a student says “five plus two”, hold up a the whole class will respond with the answer. Then ten frame with five dots and indicate with two fin- the next student will call out a different number and gers where the additional two dots would go. give the “think time” signal before the class answers. Continue around the class this way. A “think time” Variations This game has many possible varia- signal is important in this activity because it gives all tions including Combinations of Ten, (say a num- students time to respond rather than shutting down all ber and the students say how many more to make thinking as soon as the quickest student calls out the ten), Doubles, Neighbors, and Halves. Around answer. The signal can be something simple like the Class is a quick activity that can be used as a holding up one, two, then three fingers or tapping a sponge activity anytime you have a spare minute desk three times. Depending upon the activity, you or two. may want to lengthen the wait time signal. The fol- lowing example will help make the activity clear. Modifications Around the Group is good modi- fication for this activity. Students work in threes Think Two More Around the Class could be or fours (or even pairs). The teacher indicates the played after a mini-lesson adding two using a ten game (e.g. Doubles Around the Group) One stu- Appendix frame (see p. 4). To begin Think Two More Around dent calls out a number and gives the think signal the Class, the first student would choose a number and the others respond with the answer. Then the (for example, seven) and say “seven plus two” then next student calls out a number. This goes around give the “think time” signal. Once the signal is given, the group two or three times. An alternative to the class would respond “nine”. Then the next stu- having the group responding out loud is to have dent would choose a number, give the signal and the students write the answer on a personal white class would respond. Ten frames can be used to pro- board or piece of paper. Beat the Calculator In Beat the Calculator, each pair sion about how a calculator can be used to find a of students needs a calculator. sum. It is also very important that the students The student with a calculator who are trying to beat the calculator are using calls out a number and while the thinking strategies—not counting strategies— to other student tries to “beat the find the sum. Beat the Calculator Neighbors calculator” by writing down the should be played only after several mini-lessons answer before the first student can use the calculator on Neighbors (see p. 5). It may also help to have to compute the answer. students practice strategy cards just prior to play- ing Beat the Calculator. For example, when playing Beat the Calculator Neighbors, student A calls out “8 + 7” and uses the There are many variations of Beat the Calculator calculator to compute 8+7. Student B will try to beat including Think One More, Think One Less, the calculator by writing “15” before student A gets Think Two More, Think Two Less, Think Ten the answer on the calculator. Prior to playing this More, Think Ten Less (start with a teen number), game, it is important that students have had a discus- Doubles, Neighbors, Halves and Fast Nines. Page 10 Addition & Subtraction
- 11. Interval Training Interval Training is a simple, yet flexible activity that this activity and not revert to counting strategies. If can provide students with differentiated fact practice. the time constraint is too much for a student then he During Interval Training (IT), random numbers are should just record the numbers he hears and not per- called out at regular intervals of time—generally 8 form the operation until the CD track is over. Then second intervals are used, but 5 second intervals can he can have adequate time for practice using a be used when students are ready for a challenge. Stu- thinking strategy . dents write down the number and then perform a pre- determined operation on the number. Numbers can It is easy to differentiate with IT. Students who need be called out by the teacher who is watching a clock more practice with “think one more” can continue or an Interval Training CD can be used (see p. 12 for that practice (as in Fig. 1 or 2) while those who need more information on how to obtain a CD). A CD has more of a challenge can move on to other strategies. the benefit of allowing the teacher to observe students Fig. 3 shows a student who is practicing the strategy during the activity. In addition, because an IT CD has “combinations of ten”. The first number is the num- music, it tends to be motivational for students (though ber the student heard and recorded and then had to the music can be distracting to some students). Once figure out what number to write in the second blank. a routine is established, IT should take about 6 min- Fig. 4 shows practice of the strategy “add ten” and utes—two minutes for students to set up their papers, Fig. 5 shows practice of doubles. All of these strate- Appendix two minutes for the IT, and 2 minutes for students to gies can be practiced using the same CD track. check answers with a part- ner (if desired). Caution: Interval Training should be used to practice strategies that have already been developed through mini-lessons and practiced with It is important to note that strategy cards and other activities that do not have time constraints. IT should be used to prac- tice strategies that have al- ready been developed through mini-lessons or discus- sions and have been practiced with strategy cards and other activities that do not have time constraints. If a student becomes frustrated or finds this activity diffi- cult because of poor fine-motor skills, then a different practice activity should be used. A good time to start IT would be after mini-lessons Figure 3 and practice related to the strategies of Think One More. Initially, it is best to give students a preprinted sheet for IT. Later, students will be able to create Figure 1 their own forms. The first time you do IT, demon- strate the process: you write the number that is called out and then perform the operation (+1 “think one more”). As you demonstrate, model your thinking of the strategy out loud (see Fig. 1). You can say some- Figure 4 thing like “one more than six is seven, so 6+1 is 7; one more than four is five, so 4+1 is 5.” Once stu- dents are proficient with “think one more” and “think two more”, the two strategies can be combined (see Fig. 2). It is important that students use thinking strategies for Figure 2 Figure 5 Strategy Development and Practice Page 11
- 12. Resources More about Strings For more information about using strings More About Interval Training CDs All building Math Rep- for mini-lessons, we highly recommend the book Young resentatives have a copy of a locally-made Interval Training Mathematicians at Work: Constructing Number Sense, Addi- CD. Teachers are free to make copies of this CD. Note that tion, and Subtraction by Catherine Fosnot and Maarten Dolk. not all CD players will play rerecorded CDs, so be sure to try it Several copies of this book are available for check-out from the out before you plan to use it (especially if you have an older Curriculum Department (see contact infor- CD player). A similar product can be ordered from Creative mation below). For those wishing to pur- Mathematics (Kim Sutton) at www.creativemathematic.com chase a copy, it can be ordered directly You will need to order the book Math Drills from the publisher at www.heinemann.com to Thrill, which comes with a random num- ber CD. (Note that the Rapid Fire Random Number CD has numbers at 2 and 3 second intervals, so only order that CD if your class needs a real challenge!) Arithmetic Racks (Rekenrek) Although an arithmetic rack may look like an abacus, it is not used in the same way. It consists of two rows of ten cubes or beads, which are broken into two sets of five. As with a “ten frame”, the use of the arithmetic rack gives students a visual support to build number relationship—in particular, seeing the relationship of a num- ber to five and ten. An arithmetic rack can be made using Unifix cubes and string. They can also be purchased from the Math Learning Center at: www.mathlearningcenter.org/products In the keyword box, type the word “rekenrek” (Dutch for “arithmetic rack”). They are available in various forms, including large, demonstration racks and small, individual racks. For additional information or questions about this handbook, please contact math specialists Kathy Cheval or Kathy Bowers in the Curriculum Department at 503-399-3075 or by e-mail: cheval_kathy@salkeiz.k12.or.us bowers_kathy@salkeiz.k12.or.us Additional information and resources can be found on the district math website: http://is.salkeiz.k12.or.us/StaffResources/Math/MathIndex.htm Click on Investigations, then Basic Facts. Notes © May 2007 This handbook has been produced by the Curriculum, Instruction, and Assessment Department of Salem- Keizer Public Schools. It may be reproduced for the use of Salem-Keizer Public School teachers, staff, students and parents. Reproduction of this document for any other use is prohibited without written permission from SKPS.