Lesson: Addition Strategies: Doubles Plus One

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Lesson Objective

SWBAT use the doubles + 1 addition strategy.

Lesson Plan

Building Number Sense (5 minutes)

Take the day of school and build it with different coin sets, if its 25 you could build it with two dimes one nickel, five nickels, four nickels five pennies, twenty five pennies. Stress the changing in counting with each coin, nickels are by fives, pennies are by ones, dimes are by tens. Then count out each student suggested combination with the class to check them. Discuss which combination of coins the students would use and why.

Name Collection Box (Use the number from the day of school, write number in top left of box, write different “names” for that number in box; coins, base ten blocks, tallies, pictures, words, etc.)


Mental Math Fluency (5 minutes)

Pepper with addition facts (all students stand, ask each student an addition problem, when student answers correctly they sit and “earn their seat”)


Problem of the Day  (7 minutes)

Teacher (T): For today’s problem of the day make sure you use one of our addition strategies.

(For today’s problem of the day cover the problem somehow with a piece of paper, or flip it over, etc.)

T: For today’s problem of the day our focus is speed. So I am going to flip this chart paper over and there will be a word problem on the other side, when you know the answer raise your hand. [Flip over chart and read problem aloud]

Amari had 7 hair clips, her sister had 6 hair clips how many did they have altogether?

T: [Call on first hand]

Student (S): 13

T: How did you solve this problem?

S: I counted on my finger, I counted in my head, I drew a picture, OR I added 6+6 which I know is 12 then I added 1.

T: What if I told you I knew a trick that could make this problem as quick as _____ got it or even quicker AND you already have the power to use this trick? Well get ready to get quick, real quick.


Mini Lesson              (12 minutes)

(With all questions you may elicit answers from class or give answer depending on time, class, and teaching style. I prefer to have kids drive answers and all the answers written are the conclusions I will drive student conversations to. But I still keep it very teacher driven as this is the “I” do)

T: Math problems are like puzzles, and if we can figure out the trick to the puzzle than we can solve the problem very easily. Whenever you see a problem you should always think first, is there a pattern I can use to solve this equation quicker. Today we are going to a focus on a pattern you may see a lot and a pattern that is useful in many many equations.

[Write up the problem of the day equation 6+7=] Lorence solve this problem by counting on your fingers out loud go.

Lorence: 6, 7, 8…

T: Wow that took a really long time, I could have cooked my breakfast and ate it before Lorence was done counting, not because Lorence is a slow counter, but because it’s just slow to count 1, 2, 3, 4, 5, it just takes so long. There must be a faster smarter way to solve this problem, and there is. Does anybody see any patterns or shortcuts to solving this problem? (If you get someone thinking of the double 6 plus one run with them and skip to the script where it says “We call this strategy doubles plus one”. If not continue from here) Terrance what is 6+6?

Terrance: 12

T: What is 12+1?

Terrance: 13

T: Now that was quick, and did you get the same answer? Yes. Can anybody tell me what I did there? [Take some answers and discuss them]

T: We call the strategy I just used doubles plus one, and it is very useful. Whenever we see a problem that has two numbers that are one away from each other all we have to do is add their doubles and then “plus one”. Let’s look at how we do that. [write 5+6] so first thing I notice is that 5 is one away from six, so I’m going to look for the double fact, I am always going to use the lower number 5+5 we all know that is 10 (If you have a student ask about using the larger double fact say that 6+6 then minus one is completely fine but it’s just a lot easier for you to count up one than count down one so you always take the lower double fact, if it’s easier for them to count down they can do that, but for today focus on the doubles PLUS one and if you don’t like it switch to whatever way is best for you) now that I have the 5+5 what am I missing?

Teacher or Student (TS): the original equation is 5+6 we are missing one number, so we “plus one” to our “double”

T: Great but double facts don’t stop helping us there if we have two number that are two away from each other there is another doubles trick we can use. (this next part you can do depending on the culture in your room and feeling on the activity) I am going to whisper the trick into someone’s ear and then write down a problem and lets see if they can get the answer before the class. [write 7+9=] student you just told secret to gets it:16. Now I’ll share the secret with you.

If you have a numbers that are two away from each other all you have to do is find the number in the middle of them and double that, so the number between 7 and 9 is 8, 8+8 is 16. (some students might also suggest 7+7 then “plus two” this is another solid way and you may choose to actually teach doubles plus two instead of take the double in-between, up to you)

So we are going to go through a couple of problems as a class and solve them out.

[Write 3+4=]

Class: 7

T: Great we did 3+3 =6  6+1 is 7

[write 4+5]

Class: 9

T: How’d you get that?

S: 4+4 is 8, 8+1 is nine

[Write 11+9]


T=great all we have to do is find the number inbetween since 9 is 2 away from 11, 10+10=20


Go through these and do the same practice as above: 5+7, 7+8, 7+9, 11+13

Work Time (Zones, Independent, Group 30 minutes)

Group Work “You Do” (Math Zones): Each student gets attached game board, there should be the game board printed on each side. [print the document double-sided]. Students are paired up, each pair gets one 6, 10, or 12 sided die. For the first round each student rolls and then write s the double fact, if they roll a 5 they write 5+5 and solve, then X out that number on the gameboard, if the number isn’t there or already X’d out then they do nothing. (if you think your kids are good on double facts then move straight to doubles plus one) After there is a winner (the person who X’s out all their numbers first) in each group change the game to doubles plus one. The player rolls the dice and then writes down the doubles plus one fact, if they roll a 10 they write down 10+11 and solve it. When this is completed move to doubles plus two, student rolls a 9 they write down 9+11=.




Math Reflection/Share (4 minutes)

(This is a time to share work and discuss critically a problem a student had or explain student work. Also this time can be used to ask a difficult question that takes the concept taught one more level up in bloom’s taxonomy)

What is 50+51? Explain how you knew. (This is especially good if you have a hundreds chart in the room and push them to use it, they count down by tens 5 times, then remember that when two numbers are one apart you just add one.)

T: How did you solve?

TS: Well I see that the two numbers are one apart so I take the lower number, 50, and double it, I either know 50+50 is a hundred, or I draw tens sticks, or I use the hundreds chart, etc. I then just have to add one just like from our doubles plus one.


1. What went well?

2. What would you change?

3. What needs explanation?

Students were very excited at learning a “trick” and stressing that this was a cool puzzle and we have the key to solving it peaked their engagement.

I hadn’t planned for a child to come right out during the problem of the day and use the doubles plus one rule, he hadn’t been taught it, he just naturally came about it, so preparing for this and knowing how you will support and build off of this if it happens is important.

If double facts have not been introduced you will want to go over them and snapping them out quick at least through 12 or 15.

You can choose to incorporate more mental math skills into this day but I like starting out with a quick and fun mental math skill like doubles plus one that is easily implemented and a bit natural to the students.



Lesson Resources

Math Unit 2 Day 4   Lesson Plan
Math Unit 2 Day 4 Worksheet   Classwork


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