The 100-chart is a useful tool for a first grade student when working with addition.

Once again, the open number line can be used when doing subtraction.
52 – 20 = 32
− 10	− 10

32 	42 	52

The above example shows how a student may do the subtraction problem 52 – 20. The example below shows the same problem using the adding up strategy.

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Roadmap

Grade 1

14 + 30 =
This section of the 100-chart shows how a

+ 10

+ 10

+ 10

+ 1 + 1

student has started at a two-digit number (14) and added a multiple of ten (30) to find a total of 44.

Once students understand the concrete models they move to the written form. A student could solve a problem using the partial sums strategy.

20 	30 	40 	50 	51 	52

51

The student has started at 52 and counted back to 20 which shows a solution of 32.  All first graders have to continually explain their thinking.

As with addition, the 100-chart is a valuable

54 + 9 =
50 + (4 + 9) =
50 + 13 = 63

54

 +    9 
OR	13
 +  50 

63

25 + 9 = 34

+

model when doing a subtraction problem.

93 – 40 = 53

This student has started at
93 and subtracted 40 to get 53.

First grade students will add and subtract within
20, demonstrating fluency for addition and

Strategies for addition and subtraction

2013-2014

2 tens and 5 ones + 9 more ones

subtraction within 10.

Math

First grade students need to be able to count all, count on or rearrange the dots in order to add.  In this example, a child may start with five dots and count on four dots to make nine dots.  It is also
possible to see four groups of two dots to make eight dots and one extra dot to see nine dots.
• •	• •

Making a Ten

8 + 6 =

2	4
10 + 4 = 14
The goal is for students to make a ten. In this example, the child moved two dots
from the second ten-frame to completely fill one ten-frame. Four dots were left over. After much practice with the ten-frames,
the written model should be included.

10	7
Students start by building representations of a collection of 10 things to make a bundle of ten ones called a ten.  This picture shows one ten and some more
ones (7).

•••	• •

											

Break to a Ten

Working with Base 10 Blocks

Rekenreks
(Beads used for counting)

13 – 5 =

13 − 3

− 2 =

First grade students have to be able to mentally rearrange beads to model strategies for addition and subtraction. The use of rekenreks fosters instant recognition of sets (subitization), fluency and computation with addition and subtraction. In this example, the student may see 6 as 5 red beads and 1 white bead.

10  − 2 = 8
In this example, students will break the 5 into a 3 and a 2.   The 3 allows the 13 to subtract to a 10. The 2 can easily be taken away from the 10 to make an 8.

First graders also add using the doubles strategy. This example shows two ways in which students can do the problem 6 + 8.
6 + 8 =

Students build numbers using base tens. Here, a student has built the number 35 using 3 tens and 5 ones.

A first grader learns to use an open number line for addition and subtraction problems.

37 + 6 = 43

6 + 6 + 2 =
6 + 6 = 12
12 + 2 = 14

6 + 2 + 8 =
OR	8 + 8 = 16
16 − 2 = 14

41

3•8   3•9 	4•0 	•

4•2 	4•3