Primary Math//Addition & Subtraction Strategies
Addition Strategies in Grade 1
Based on Carole Fullerton’s “Mastering the Facts: Addition“
It is great making real life connections with math, through math story books (One is a Snail, Ten is a Crab) as well as using numbers are objects (I have 3 teddies and I got one more for my birthday, how many do I have?) as well as using numbers are money talk (I have 5 dollars, if I had double that amount, how much would I have?)
Plus 1 (adding 1)
- We can count on from any bigger number. When we say the number that comes next, we are adding one.
- Mathematicians know that adding one makes the set of one more.
- Students enjoy singing the Sharon, Lois and Bram (French/English) song “One elephant, deux éléphants”
- Mathematicians know that two equal sets put together make a new amount. We call this amount a double.
- The doubles are an important set of facts.
- When we add the same amount twice, we make a sum that is double.
- We make connections to doubles around us in the world and imagine them to help us remember.
- 3+3 (legs on a lady bug)
- 4+4 (legs on a spider)
- 5+5 (fingers on each hand)
- 6+6 (eggs in a carton)
- 7+7 (2 weeks on the calendar)
- 8+8 (crayons in a crayola box of 16)
- 9+9 (wheels on a semi)
Presque Doubles (Near Doubles)… better known as doubles + 1
- Mathematicians know that when we know our double facts, we can use that strategy to add numbers that are near doubles.
- For the near doubles, we find the closest double fact then add one more.
- Students search for neighbours: 6+7 or 3+4
- Double the SMALLER number and add 1
Les Amis De 10 (Make 10, Ten Friends)
- Mathematicians know that it is easier to add and subtract when you know the parts of ten.
- When we name that parts that make ten, we are naming the complements.
- We can “see the parts of ten on a ten-frame
- When a ten frame is filled to 7, the student notices that there are 3 empty spots: 7+3=10!
- We also play a quick flash card game with ten-frames called ” I WANT 10.” Where students see a ten-frame, 2 for example, and I say “Ma maman m’a donné 2 biscuits(My mom gave me 2 cookies) and they yell out “Je veux 10!!” This is followed by them saying how many more we want to make 10
- this game can be played with 10 frames, 6 or 10 (ideally dice), playing cards
Plus 10 (add 10)
- It’s easy to add tens!
- The “ten and” facts are the teen numbers (but in French a bit more complicated)
- Mathematicians know that adding ten changes just one digit of the sum.
- We use a full ten frame and part ten-frame (ten and some more), as well as place value tent cards to help us visualize the place-value concept: that the 1 in 13 means ten
- To print at home: adding ten tents
9+ et 8+ (bridge through 10)
Plus 2 (add 2)
La Scie (the “two aparts” or the “in-betweens”)
Les 2 Derniers (the last 2 facts)
Subtraction Strategies in Grade 1 (to 10)
Based on Carole Fullerton’s “Mastering the Facts: Subtraction“
Students will masters subtraction facts over grades 1-3.
In Grade 1 students are introduced to the idea of subtracting as removal and comparison.
Soustraire Les Doubles (Get to Zero: Subtract The Doubles)
- Subtracting ALL: Start with 4 take away (all) 4 left with nothing: 4-4=0
- We take away as many counters as we started with
- Create stories where student get to zero: I had 10 dollars and I spent it all! How much do I have left?
Un De Moins (One Less)
- Counting down by 1
- Using a number line show one jump backwards, taking one counter away, or by using the subtraction symbol.
- When we subtract by one we say the number that comes before.
- Game: roll a dice (6, 10, or 12 sided) and say “3! 3 take away one is 2!” (en Francais: 3! 3 moins un égale 2!)
- Create stories where students take away one: I had 5 candies and my brother ate one. How many candies do I have left?
- Pete the Cat and His Four Groovy Buttons : He looses his buttons ONE at a time! Perfect!
Moins 2 (Two away: Take Away 2)
- Start with even numbers which helps with counting backwards by 2s
- Number lines help show two jumps backwards
- Play the game from One Less but this time take away 2.
Stop here! The goal is that your child has a response in 3-second for these 3 facts.
Les Voisins (The Neighbours)
- Numbers that are “next door” are right next to each other. Their numbers differ by 1. One number is one bigger than the other.
- The difference between 9 and 8 is one. 9-8=1. La différence entre 9 et 8 est 1.
- This strategy is to allow students to see numbers in a row vs counting down or taking away the smaller number (9 counting down 8 to 1).
- Students might find the answer by counting up.
- Game: flip two dominoes, if the dominoe is a neighbour say the subtraction sentence (5-4=1: Neighbours!) (5-4=1: Voisins!) and keep both. Take turns and whoever has the most dominioes in the end wins.
Les Presque Voisins (The Near Neighbours)
- Add up to find the difference between numbers that are 2 away
- Students will come to decide that counting up by 2 is easier than counting back by 5 (7-5=2) and later decide in problems which strategy to use
- Game: have X number of counters and cover up all but two. How many are hiding? Record equations: (example) 10- ____ = 2
Les parties de 10 (Parts of 10)
- Les Amis De 10 (Ten Friends) in subtraction
- With ten frames students see the missing part. Ex: 8 on a ten frame has 2 empty squares: 10-8=2
- Using ten frames, have students come up with the equations of 10- ___=___
- Use word problems: I had 10 freezies and 6 melted, how many are still frozen? How do you know?
Moins 5 (Take Away 5): Ten Frame strategy
- Students need to use a ten frame in order to visualize the 5 being taken away (which is the full top row of a ten frame)
- Equations will be with numbers bigger than 5: for example 8-5 or 6-5
- As we go along students are able to use multiple strategies to find the answer. For example 7-5 is a take away 5, as well as a Nearly Neighbours. The goal in the end is to not count back 5 but instead to use the most efficient strategy.
- Use word problems (and draw them out!): My sister has 9 teeth and lost 5 of them, how many teeth does she have left?
Arbre de Soustraction (Subtraction Family Tree)
- How can 9 apples be in two trees? 8/1, 7/2, 5/4 etc
- If we can see how many apples are in the one tree but not the other and we know there should be 9 all together, how many are in the hidden tree? (Ex: 9= __+5 or 9= 4+____) then move onto 9-5=___ how do you know that?
- When we subtract we are looking for the missing part. We make connections to what we know in addition to find the missing part in subtraction.
- Subtraction Tree (Arbre De Soustraction) are the number families that are all represented together: 9-3= 6, 9-6=3 as well as their addition counterparts.
If we have time// A little challenge before grade 2
Moins 10 (Take Away 10): Facts to 20
- By using two ten frames: one full (10) and the other part (1-9) the students see the visual representations of taking away 10 and seeing how many is left.
- The digit in the ones (unités) stays while the tens (dizaines) gets taken away.
Moins 11 (Take Away 11): Facts to 20
- Just like Moins 10 (Take Away 10) students need to think of taking away ten and one more