Lesson: Introduction to Addition Strategies

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Lesson Objective

Introduce multiple addition strategies such as tallies, fingers, pictures, numbers, mental math, etc.

Lesson Plan

Building Number Sense (5 minutes)

Counting Circle (create a circle of shapes drawn on the white board or chart paper, student groups of 4 to 5 students each choose a shape to start on, teacher points to that shape, students receive a value to count to by increments (“Count to 20 by 2’s”), teacher points to each shape around the circle as the whole class counts for the group, if the count ends on a triangle that groups gets a point if it ends on another shape, the shape is erased and no points are awarded, another group is now up)

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)

Jamari had six Bakugan toys and his mother bought him 5 more, how many toys does Jamari have altogether?

T: How did you know if this was an addition/subtraction problem? (Buying means you’re getting more, altogether is a vocab word that is usually in addition problems, etc.)

T: When you knew it was addition how did you solve it? (I wrote 5+6=) but how did you know how much that was? (Did it in my head, on my fingers, etc.) What are some other ways you could have solved it? (take so answers) Great there are a lot of ways we can solve addition problems, we are now going to dive into these different strategies.

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)

 

When we solve addition problems there are many ways we can solve them. Some ways are easier than others. Here are some strategies we can use in addition:

Numbers:

Pictures:

Fingers:

Tallies:

Hundreds Blocks:

Brain (Mental Math):

(write all the strategies on chart paper)

Numbers- Now let’s take a look at how each of these work (write 11+6 at top of chart paper) so let’s first look at numbers, so we write 11+6=, now when we use numbers we can break up our equation into more or less numbers, so we could break this one into 10+1+6=, 1+6 is 7 and 10+7 is 17. When we use numbers we try and figure out the easiest numbers to use and put them together or break them apart (this is a skill that will be gone into in more detail later so don’t spend too much time here)

Pictures- Now let’s draw pictures, what pictures should we draw? (We can use anything since we aren’t given units we can draw whatever we want) Draw 11 circles and then 6 circles preferably in different colors or in an addition sentence. Now we just need to count up all of our circles. 1, 2, 3, 4,…. Boy that took a long time

Fingers- next we can use our fingers, we should start at the number we can’t make with our fingers, 11 and then count up six fingers. 12, 13, 14, 15, 16, 17. That was a little quicker. But what if our problem had two numbers over ten, could we use fingers? (We could but it would be very difficult, fingers are good for numbers under ten)

Tallies- Now onto tallies, so when we make tallies we draw four lines then cross them with the fifth, so we make groups of fives and/or ones. How do we make 11? (two groups of 5 one 1) how do we make 6? (one group of five and one one) Can anyone think of a quick way to add up our tallies? (Count the fives, five ten fifteen, then the ones sixteen seventeen) Wasn’t that so much quicker to count than pictures and we can use it with numbers even over ten!

Hundreds blocks- What will we draw for our 11? (one ten and one one) What about our 6? (Six ones) now we count them up, first we need to remember we have a ten here, so count that first then the one: 10, 11, 12, 13…. How are hundreds blocks similar and different from tallies? (grouped into ones and tens instead of ones and fives) What do you think hundreds blocks could be better for? (Larger numbers especially those over a hundred)

Brain Mental Math- This one is going to be different for everybody, what do you see or do in your head? (Go around the class and talk about what we do in our heads ex: I see hundreds blocks and count them, I see pictures, I add the 1 and the 6 then add that to the ten, I count up six from 11, etc.) Great those are all right answers, in our head we just need to do what makes the most sense and is easiest to us.

Let’s take a look at a problem and try to figure out the best strategy:

Let’s take a look at an addition problem: 1+1=

What is the answer (2) how did you know that? (I know that when you add 1 to a number you can just count one past that number, I held up one finger than another, I solved it in my head, etc.)

What was the quickest way to solve the problem? What was the easiest way? Talk about all the different ways and their strengths and weaknesses. Hold up your fingers was quick but took a little longer than doing it in your head, or just counting up one more. Writing down or using manipulatives took the longest. So which strategy should we use? It really doesn’t matter, whatever strategy you feel the most comfortable with, is quickest, and easiest for you is the one you should use, let’s look at some tougher numbers:

 

Go over each strategy with these questions:

 

Who used this strategy? Why did you use this strategy? Do you think this was the best strategy, what would be a better strategy? Why?

Work Time (Zones, Independent, Group 30 minutes)

Now we are going to practice our strategies together as a class:

Look on your worksheets at 10+11= we are going to solve this problem using all of our strategies.

Have students decide which strategy is their favorite then defend their choice to a partner. After that go through and use every strategy together as a class, have students guide you through how to do each strategy. Ex: So with tallies how am I going to start? Write the numbers. Ok now what do I do? Draw the tallies. How do I do that? Draw four down and then one across in groups of five. Then what do I do? Count them up.

Go over each strategy with these questions:

Who would have used this strategy? Why did you use this strategy? Do you think this was the best strategy, what would be a better strategy? Why?

Students will be working on their own, or in pairs, choosing what strategies they want to use: 13+5, 9+8, 4+2, 8+0

Teacher should work with a targeted small group or circulate and ask students what way they chose to solve the problem, why they chose that, is there a better way, is there a worse way, why? (These question can be whole group or partner share)

 

Group Work “You Do” (Math Zones): All groups (of 2 students each) play addition top-it. First student draws two cards and adds them together both students solve the problem using their own strategy and check each other’s work.  Second student draws two cards and adds them together both students solve the problem using their own strategy and check each other’s work. Whoever has the larger sum keeps all four cards. Person with the most cards when there are no more cards left wins, start over by mixing up deck and drawing again.

 

 

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 strategy would you use for 100+5?

(I would use hundreds block because all I need to do is draw a hundreds block and then five ones and count them up. I would use mental math and count up 5 from 100 because that is easy for me to count. I would not use tallies because it would take too long.)

It could be helpful here to solve using some not so efficient strategies like tallies or pictures, after drawing 20 circles I would say “Boy my hand is getting tired, do you think this is a good way to solve this problem?

 

(If students are not into hundreds yet 50+5 is another good pair to use)

 

1. What went well?

2. What would you change?

3. What needs explanation?

Students enjoyed trying multiple strategies to solve one problem, this also gave them a better grasp of the concept of addition.

I did not use the attached work sheet, student written work was a bit disorganized and hard to assess because of this.

The use of tens blocks needs to be explained thoroughly the use of them is a very easy  segue for kids going into double digit addition, need to make sure and go explicitly over why we use tens blocks and how much easier they make a problem like 10+11. This will be given much more attention tomorrow but it’s worth referencing it’s importance in this lesson.

 

 

Lesson Resources

Math Unit 2 Day 2 Worksheet   Classwork
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