Books and Base 10

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SWBAT explain which cube arrangements help them solve story problems more efficiently.

Big Idea

Head to the library and figure out how many books are stacked up! Students look back at their strategies from yesterday's lesson and revisit the best ways to solve these problems using what they know about place value!

Setting Up the Learning

5 minutes

Review prior content: Show students how this relates to prior learning

We have been learning about place value-how many tens and ones are in a number. We have also learned about solving story problems. Today we are going to think about how place value can help us with story problems.

Connect: Show students how this connects to the bigger picture

In second grade, you are going to be working on solving story problems with these big numbers all year. The work you do today will help you prepare for this.

Objective: Explicitly state what students will learn

Your thinking job is: How can I arrange my cubes so that they make solving problems easier?

Opening Discussion

10 minutes

This lesson builds on what student's did the day before. Check out that lesson here!

Let’s reread this problem from yesterday. We are going to look at how a few people solved it and then discuss what we notice about how they are solving it. Our brains need to be thinking about the strategies so they can learn from the strategies also!

“You are at the bakery with your family. You buy 40 blue cupcakes and put them in your car. Then you drive to another bakery and buy 20 pink cupcakes and put them in your car. How many cupcakes do you have in your car?”

I'll choose 3 strategies from the day before.

See attached Strategy Level Guide for how students may have solved this problem. All of these strategies are based on things I am seeing in student work.

The focus of the strategy share is to push MP3, Construct viable arguments and critique the reasoning of others. Students are explaining their thinking, while also having to compare and contrast their own thinking to others' in the room!


Guiding Questions:

  • How did they show the 20 in this strategy? How is that the same/different from how the other strategy showed 20?
  • Why did this person show these numbers using groups of 10? Why did they count the bars by 10?
  • Which strategy is a little faster? Why is it a little faster?
  • How did this person count? Some students may count all by 1s, some may count all by 10s, some may count on by 10s.
  • Partner Talk: How did this person solve the problem?



Student Work Time and Share

15 minutes

Today I have a different problem for us to try to solve together. You are going to get a chance to either try a new strategy or practice the strategy you tried yesterday.


I am getting ready to have a yard sale. I have 52 magazines and 30 books that I want to sell. How many magazines and books do I want to sell?

Partner talk: Right now, I don’t want you to share what you think the answer is. I want you to tell your partner what you are going to do to solve it.


Student Work Time: Students solve the problem at their desks and show their thinking. Students have unifix cubes at their desks. Students who are already using the concept of 10 can have base ten blocks or number sentence.


Student Share:

  • Partner Talk: Show your partner what you did. Explain your strategy.
  • See attached picture of how a few students shared and the chart we made to remember their thinking! I like to hang these charts up so kids can use them as a mental road map for later problems.



Independent Practice

15 minutes

Each group gets 3 problems to solve. I will differentiate the problems using number size. You can see how I solved the problems below. You will see that each problem requires students to explain in writing how they solved. This is aligned to the CCSS vision of writing across the curriculum

Group A: Intervention

Numbers under 40

Group B: Right on Track

Students get higher on the decade numbers that encourage counting on. For example-50 and 20, 50 and 40, etc. Students are likely to use 50 as a starting point. 

See attached video of how one little boy in this group is using counting on as a strategy. This is exactly where a Group B student should be at this point in the year! He still needs the blocks, but he doesn't have to count all of them. 

Group C: Extension

S get numbers with numbers in the ones place. The ones don’t add to a ten yet. For example, 51 and 42, 51 and 34, etc. 

See Group C video attached! You'll see how she is starting to combine tens first and wrote a cool number sentence to match!

See attached story problems!I left blanks for the numbers so teachers can write in the numbers that are best for their students before copying!


8 minutes

We will end with a quick, number sense game. This game is excellent for helping students subitize large numbers. It also helps them understand the concept of base ten, which is the most important concept within the first grade Common Core standards!

We play using the ten frames. You can go to this website to do Ten Frame Flash for free on your smart/promethean board!


  1. Flash for a few seconds.
  2. Ask students: “How many dots?” or “What number did you see?”
  3. How do you see the number?/How do you know?