2nd Grade Math: Unit 3

October 12 and October 26, 2017 /Subtraction Up To 1,200

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Disregard the word 'borrow' in the video instead we use the term regroup.... 'borrowing' misrepresents what is taking place.


I have included this mat in your small group folder

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Regrouping ones and tens work mat

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Using crayons | Addition and subtraction within 100 | Early Math | Khan Academy
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2.2 Number and operations. The student applies mathematical process standards to understand how to represent and compare whole numbers, the relative position and magnitude of whole numbers, and relationships within the numeration system related to place value.

2.4B add up to four two digit numbers using mental math strategies based on knowledge of place value.

2.4C solve one step and multi step word problems involving addition within 1,200.

2.4D generate and solve problem situations for a given mathematical sentence involving addition.-Math Journals Write a math story for 126+83=

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Do you want to create and keep your sentence stems for future lessons/years then use this resource! It is a resource I have used for many years as an interventionist and just remembered recently to revisit, it’s called senteacher.com. You will be able to create sentence stems and vocabulary words you can then copy on card stock and laminate if you wish for years of use. You can make large sentence stems or smaller ones it’s up to you..if you want you can punch holes and keep then in a ring per unit for students to access as well when working independently or with a partner. Come by my room if you want to see some samples….:)

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place value, chart, part, number sentence, equation, algorithm, equals,subtract, whole, minus, is the same as, relationship, difference

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Start with a story:

Mrs. Ochoa's class has 337 Dream Box points. Mrs. Sander’s class has 179 less points than Mrs. Ochoa’s class. How many Dreambox points does Mrs. Sander's have?

Represent the number sentence using the place value names-PVC CHART

Represent the whole number using pictures (models) VM, base ten blocks and PV chart:

Connect to a Visual Model/Number Bond/Part-Part/Whole/then transition to number sentence :

Reinforce vocabulary-label and discussions

Use terms: regroup ....not borrow...

All lessons:

Whole Group:

Virtual Manipulatives


Number Sentence(s)

Small Group:

Math Story

Place Value Charts/Mats

Base Ten Blocks

Math Journal/Recording sheet( min. twice a week)

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Focus: Expose your students to at least TWO different methods for subtraction

Number Line, Place Value Chart, OR Traditional Algorithm w/pictorial

The goal is to to allow students to develop a deeper understanding of the concept.

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Additional Small Group activities for the unit are in the Unit Documents (Schoology-second grade group)...use for small groups

Discussion, Turn and Talk, journal/recording sheet entries..

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Think Central Manipulatives

Use Think Central's virtual manipulatives as well...for regrouping, etc...
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Glencoe Virtual Manipulatives

Sander's share from last year
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Break a Hundred (MIF Book)-Lesson Three-Subtraction with Regrouping Ones and Tens

Break a Hundred! (Same materials as Make a Hundred!) Students will start at a hundred with 9 tens and 10 units, roll the die and subtract (remove) that amount from a hundred. The first one to get to zero or closest to zero wins!
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Lesson One: Subtraction without Regrouping

In whole and small groups always start with a story. Conceal the numbers so that students may focus on the math story and improve on their comprehension. Give students the opportunity to turn and talk about what they have read and understand of the story.

Ask questions: What do we know about the story? (some fish are orange, some are not...)

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Reveal the numbers..

After you reveal the numbers, read the story again and once again ask students to turn and talk what they understand about the story now.

As questions: What do we know? ( We know how many fish are in the pond and how many are orange) How many are orange? What are some colors the other fish could be? (red, blue. black,etc) How can we find how many are not orange?

Subtract, take away, less ____

Write the title' Subtraction without Regrouping'

Create anchor chart/SB copy with students, anchor chart should include:

  • Place Value Chart-Students share how to make the chart
  • Pictorial-students volunteers can come up and draw the base tens/Virtual maipulatives, Base Ten Blocks
  • Number sentence/Number Bond/Bar Model-at least one or all three
  • vocabulary words-label
  • Solution statement-students turn and talk and share the statement.
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Open a free account with education.com for great math games that build conceptual understanding

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Books-can be incorporated to enhance a lesson (read a portion, students can check out, etc)

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Friends of Ten

We created the anchor chart you see by using two-color counters on a ten frame. We put out ten red counters and I asked the students how many yellows we would need to put on our ten frame to make ten. Zero. We added 10 and 0 to our chart and wrote the equation, 10 + 0 = 10. We cleared the board and put out nine red counters. How many yellows to make 10? The students put out one yellow counter to show that it would take one more to make ten. We added 9 and 1 to the anchor chart. We continued this process until we had all the “friends”. I drew the “rainbow” to show the connections in the equations. Lots of oohs and ahs. First graders are easily amused.
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Nov 8/9

FACT FLUENCY Test-Combinations to 10

The first fact fluency test is on Thursday, October 26.

Display with stars of the students who have mastered that skill.

*students who did not will try again in November.
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The first EDC test will be on Friday, October 27.