Page 145 - NUMINO TG_2A

Activity 1 Missing Addends

jOb ective Find missing numbers in addition sentences.

1. Textbook Instructions Activity 1 Missing Addends

Have students find missing addends using 1 Use the figures to find the missing addends. Addend means
various methods and complete addition a number that is
sentences. added.

12 + 7 = 19

1. The first method for finding the missing So, the missing addend is 7 .
addends is “using the figures.”
As shown in the diagram, if the number is a
small, students can just count and figure out 7 + 9 = 16
the missing addends.

Finding the missing addend in 12 19
Count 19 boxes and mark them.
Draw circles in the empty boxes. b
Count the number of circles drawn. 9 + 11 = 20
The number of circles is the missing
addend.

1c. After grouping 8 from 15, the remaining 7
is the missing number.

8 7 15 c +?
8 + 7 = 15

78

2. Build Understanding

Missing addends

Finding missing addends is difficult for some students because they are used to finding sums for addition

sentences. So, students can get confused when they see 12 19.

The ability to find missing addends depends on one’s understanding of the function of equal signs and the
ability to equal out the total number on both sides of the equal sign. This is the basis of algebra and
arithmetic.

128 NUMINO Teacher s Guide