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Notes on Using Digi-Block with Everyday Math L E S S O N N o

Everyday Math

DB-25

2.1ConnectionIn Section 1 (Teaching the Lesson), students review addition and subtraction and the fact that they are inverse operations. They study how they can applythis relationship to fact families .

Materials single blocks small holders Math Journal 1, p. 29 Know Your Number Model activity sheet (next page)

Lesson

Review with students the meaning of the equal sign and write variousmodels for observation and discussion. Students may nd the followingparticularly confusing: ___ = ___ - ___ .

Review the symbols and positioning of numbers on the fact triangles inMath Journal 1, p. 29 to ensure that all know that the sum is at the topwith the *.

Model #1 (14*, 8, __) with one small holder lled and four additionalblocks. The fact triangle shows 8 as one addend, so students should leave8 in the holder and count all the remaining blocks to gure out the secondaddend. Students complete the number models paying close attention tothe operations symbols and the placement of the equal sign.

Have students model #2 as above and ll in the four number models.Remind them to pay careful attention to the operations symbols and tothe placement of the equal sign.

After students complete #3 on p. 29, have them complete the Know YourNumber Model activity sheet before completing #4-6.

Digi-Block Notes forLesson 2.1

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A C T I V I T Y

S H E E T

Name ______________

DB-26 for Lesson 2.1

Know Your Number Model

For each fact family, first fill in the blank for the missing sum or addend and then draw the two addendsas two different colors of single blocks.Some will be in the holder and some extra will be outside.Next, fill in the blanks for number models, paying careful attention to the operations symbols andplacement of the equal sign.

example:16,9,______

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

______ ,7,6

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

11,______ ,4

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

______ , 8,7

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

12,3,______

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

17,______ ,9

____ = ____ + ____

____ = ____ + ____

____ = ____ - ____

____ = ____ - ____

7

16 9 7

16 7 9

9 16 7

7 16 9

Student Book p. 9