Grade 1 Important Math Information
Addition and Subtraction to/from 20 and Equations
Dear Family,
We are beginning a new unit of study in mathematics called Addition and Subtraction to/from 20 and
Equations. This unit of study focuses on composing numbers with two or three addends, interpreting addition
and subtraction story problems, finding missing numbers in an equation, and telling time to the hour. Students
should be able to show and explain their work. The specific learning goals your student will be working toward
are listed below with examples of student work showing understanding of each learning goal.
Learning Goal: Show and effectively solve addition word problems with totals to 20, including problems with
unknown parts.
Example Problem
Example Student Solutions
Draw Pictures
Use a Number Line
“I started at 3 on the number line and
counted on 8 more until I got to 11.”
Rosa had some shells.
Max gave her 3 shells.
Now Rosa has 11 shells.
How many shells did
Rosa start with?
“I drew 3 circles to show the shells
Max gave Rosa. Then I drew more
circles to make a total of 11. I
needed to add 8 circles to the 3 to
make 11.”
Learning Goal: Show and solve subtraction word problems with totals from 20, including problems with
unknown parts.
Example Problem
Example Student Solutions
Draw Pictures
Use a Number Line
Tina had 11 stickers.
She gave some stickers
to her brother. Now
Tina has 7 stickers. How
many stickers did she
give her brother?
“I drew 11 circles for the
stickers. I crossed off
circles until there were 7
left. I crossed off 4
stickers.
Tina gave her
brother 4 stickers
“I started at 11
on the number
line. I counted
back until I got
to 7. It took me
4 jumps.”
Tina gave her
brother 4 stickers
Learning Goal: Find the missing number in an addition or subtraction equation.
Example Problem
What number makes
the equation true?
Example Student Solution
12 = ? + 5
12 = 7 + 5
12 = ? + 5
CCPS Elementary Mathematics
“I kept 5 in my head and
counted out blocks until I got
to 12. It took me 7 blocks.12
equals 7 plus 5. The missing
number is 7.”
Learning Goal: Break apart numbers to 20 in more than one way.
Example Student Solutions
Example Problem
“I know that 10 + 10 = 20 so
there could be 10 boys and 10
girls. To find other ways, I
picked a number less than 20
for the boys and then counted
up from that number to 20 to
find the number of girls.”
There are 20 students
in a class. Some are girls
and some are boys.
How many of each
could there be?
Learning Goal: Tell and write time to the hour.
Example Problem
What time is it?
Example Student Solution
It is 3:00.
“The minute hand is on the
12 so it must be a new
hour. The hour hand is on
the 3. It is 3:00.”
Mathematical Thinking and Practices Learning Goal: Show thinking using pictures, numbers, and
words.
Things you can do at home to support your student throughout this unit of study:
•
How Many am I Hiding?
Place up to 20 small objects (paper clips, coins, etc.) in your hand. Ask your student to
count the number of objects that you have in your hand. Hide some of the objects in
your other hand and show your student what is left. Ask your student to determine
how many objects you are hiding.
•
Tell Time
Have your student practice telling time to the hour. Ask your student what time you
eat dinner. (example: 6:00) Have your student write the time in digital format and
show the time on an analog clock.
•
Explain Thinking
Encourage your student to explain his or her math thinking with you. It is important
that students solve math problems accurately and in ways that make sense to them.
•
Math and Literature
Here are some children’s books that contain ideas related to our work in this mathematics unit of
study. Look for them in your local public library and read them together.
o Fish Eyes by Lois Ehlert
o 12 Ways to Get to 11 by Eve Merriam
o Math for All Seasons by Greg Tang
CCPS Elementary Mathematics