Curriculum Tie:


Summary: This lesson provides a compilation of activities for several subtraction strategies that may be used throughout the year.
Main Curriculum Tie: Mathematics Grade 2 Strand: NUMBER AND OPERATIONS IN BASE TEN (2.NBT) Standard 2.NBT.7 Add and subtract within 1,000 using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting threedigit numbers, one adds or subtracts hundreds and hundreds, tens and tens, and ones and ones, and that it is sometimes necessary to compose or decompose tens or hundreds. Materials: Number Line
Fishing for Less
 Deck of cards with face
cards removed, or 110
number cards
Count Back the Dots
 Two dice (one marked
with the numerals
4,5,6,7,8,9; the other
marked with, two each
of, one dot, two dots,
three dots, in the
formation of regular dot
dice.) If blank dice are
not available, use 3” x
5” cards to make two
sets of dot cards and
numeral cards. Place
the numeral cards in
one pile and the dot
cards in another.
 Count Back the Dots worksheet
Literature Subtraction
 Book, song, or finger
play
 Paper
 Pencil
Concentration Game
Double Toss
TicTacToe
 Paper
 Pencil
 Chips/counters (2
different colors)
 Spinner 19
Three Strikes
Climbing Up the Number Line
Count the Missing Objects
 Small objects
(cubes,
paper clips, beans, etc.)
Additional Resources
Books
 Subtraction Action, by Loreen Leedy; IBSN 0823413071
 Ten Little Garden Snails, by Beverley Randell; ISBN 0435049321
 Ten Sly Piranhas, by William Wise; ISBN 0590481231
 Five Little Sharks Swimming in the Sea, by Steve Metzger;
ISBN 0439592283
 Elevator Magic, by Stuart Murphy; ISBN 064467090
 TicTacToe Three in a Row, by Judith Bauer Stamper;
ISBN 0590399632
 Hershey’s Kisses Subtraction Book, by Jerry Pallotta;
ISBN 0439337798
 Shark Swimathon, by Stuart Murphy; ISBN 006446735X
 Monster Musical Chairs, by Stuart Murphy; ISBN 0064467309
 Little Number Stories Subtraction, by Rozanne Lanczak Williams;
ISBN 1574710087
Attachments
Background For Teachers: Using subtraction strategies helps children understand and learn the
basic facts.
Examples of subtraction strategies:
 Subtracting 0
 Counting back 1, 2, 3
 Subtracting doubles
 Subtracting from 10
 Counting up
These strategies should be taught and retaught using many different
methods and manipulatives. Herein is not a single lesson, but a
compilation of activities for several of the strategies that may be used
throughout the year.
Intended Learning Outcomes: 1. Demonstrate a positive learning attitude.
5. Understand and use basic concepts and skills.
6. Communicate clearly in oral, artistic, written, and nonverbal form. Instructional Procedures: Invitation to Learn
 Ask the question, “How many more (or less) girls than boys are
there in our class?” Other examples may include, “How many
students have long sleeves/short sleeves?” “How many students
have shoes that lace/don’t lace?,” etc.
 Have the girls in the
class stand in a straight line. Have a boy
stand beside a girl, becoming her partner. Any student who does
not have a partner stands in a separate group. The students can
now see which group has more.
Instructional Procedures
Counting Back
Counting back is a strategy used for subtracting. Students start with
the largest number and count back the number being subtracted. This is
an efficient strategy when subtracting 1, 2, or 3.
Counting Back 1, 2, 3
 Have the class count back from 10 to 0.
 Say a number. Ask students to
tell you what number comes before
it. Explain that the number before is 1 fewer, or 1 less.
Use the terms 1 fewer and 1 less interchangeably, as students need to
understand both terms.
 Show multiple subtraction problems using subtract
1
(e.g., 10  1 = 9, 5  1 = 4).
 Repeat the activity using subtract 2 and
subtract 3.
Use Number Line
 Have students place a counter on a number on the
number
line.
 Have students move their counter down 1 less.
 Have them say the equation
(e.g., 8  1 = 7).
 Repeat this activity, subtracting the numbers 1, 2 and
3.
Fishing for Less—Variation on ‘Go Fish’
 Students
play in groups of two to four.
 Each student is dealt 5 cards. The remaining
cards are placed
facedown in a pile.
 The first student chooses a card from his/her hand.
S/he asks a
partner if s/he has a card that is one less (e.g., If the student has
a 4, s/he would ask, “Do you have a card that is 1 less than 4?” If
player 2 has a 3, s/he gives that card to the first player.). The first
player places the match in front of him/her and continues to play
until s/he can no longer get a card that is one less than a card in his/her
hand. S/he then draws a card from the pile and his/her
turn is over.
 The game is over when all of the draw pile is gone and students
can no longer make a match from cards in their hand.
Count Back the Dots
The addition version of this game, It’s A Fact!, was introduced
during the 2004 Elementary CORE Academy.
 Students play in groups of three.
 Before playing the game, students need
to spend time rolling
the dice (explained in Materials) and counting back. Start with
the die marked with the numerals and count back the dots on
the other die. After some practice, ask the class to determine
the smallest and largest number that can be rolled with these
dice. Have them predict which total they think will come up
most often if they roll the dice 30 times. Have them explain
their thinking.
 Give each group one set of dice and one Count Back
the Dots worksheet.
 One student rolls the dice, another determines
the total, and the
third marks the tally by the appropriate number and records the
roll. After ten rolls, the children rotate duties so that by the end
of 30 rolls each student has participated in each task.
 After 30 rolls,
students count the tallies for each number and
record it on the bar graph at the bottom of the worksheet.
 Record each team’s
totals on a class graph. Did any team
correctly predict which total would come up most often? Discuss
why the graph looks the way it does. Do any of the individual
team graphs look like the class graph? Would the graph look the
same if the game was played again?
Literature Subtraction
 Find a book, finger play, or song that counts
back one at a time.
Some examples include “Ten in a Bed,” “Ten Little Monkeys,” or
Ten Sly Piranhas.
 Sing or read for enjoyment first.
 Give each student a piece of paper
and sing or read it again.
 Have the students write an equation each time
a 1 is taken away.
 Students write the equations in a column so they can
easily see
the patterns (e.g., 10  9 = 1, 9  1 = 8, etc.).
Subtracting Doubles
Concentration Game
 Students play in groups of two to four.
 Place all of the cards face down
on a flat surface in a 4 by 6 array.
 The first player turns over an answer
card. S/he must tell his/her
partner what “subtracting doubles” problem they are looking
for.
Example: If a 3 is drawn, they say, “If I double
3, I get 6, or
3 + 3 = 6, so the subtracting doubles problem that
I’m
looking
for is 6  3.” A partner states whether s/he
agrees or disagrees.
If s/he agrees, the player turns over a subtraction
problem
card. If it is a match, s/he keeps the cards and it
is the next
player’s turn. If it is not a match, the cards are turned back
over and play moves to the next person.
 Play continues until all cards
have been matched.
Double Toss
 Students play in groups of two to four.
 The first player tosses a counter
onto the Double Toss Board.
S/he uses that number to create a subtraction sentence using
doubles. For example, if s/he lands on the number 12, the student
says, “12  6 = 6.” (If the student lands on a line, use the
number
that the counter touches the ‘most.’)
If the number sentence is
correct, the student places an “X” on
the number 12 on his/her
Double Toss Tracking Sheet or a scratch paper with
even numbers
218 written down.
 The second student then takes his/her turn and play continues
until one player has marked off all the numbers.
Subtracting from 10
TicTacToe
 Students play in groups of two.
 Draw a TicTacToe board and place one
number in each space.
Use every number 19.
 Each player chooses a different color of chips.
 The first player spins
the spinner and subtracts that number
from 10. After the student has solved the subtraction problem,
s/he places a chip on the correct number on the game board.
The next player spins the spinner, solves the problem, and places
his/her color of chip on the game board. If the number is already
covered, the student looses a turn. The game continues until a
player has TicTacToe—three in a row. If there is no three in a
row, the student with the most chips on the board is the winner.
Three Strikes
 Students play in groups of two to four.
 The first player spins the spinner and subtracts that number
from 10. That player places a chip on that number on their
Three Strikes game
board. The next player then takes his/her
turn. If a student is unable to cover a number because it is
already covered, s/he places a chip on a strike. The game
continues until all of a student’s numbers are covered, or a student
has three strikes. The student with the most chips on his/her
board wins.
 If the game ends because a student covers three strikes, the
player
with the most chips wins (not counting the student with the three
strikes).
Counting Up
Climbing Up the Number Line
 Give each student a number
line.
 Say two numbers and have the students
point to them on their
number line. Have them determine the smaller of the two
numbers.
 Have students count up numbers as they move their left finger
to
join their right finger. Remind them that this is the difference
between the two numbers.
 Repeat with many different pairs of numbers.
Count the Missing Objects
 Play with a partner.
 Have students place a group of small objects in
front of them (for
this example use 15). One partner counts the objects, then closes
his/her eyes.
 The other player removes some of the objects (e.g., 6). The
first
player counts up to find the number of missing objects (e.g., 9 are
left, start at 9 count up 10, 11, 12, 13, 14, 15. We counted 6
numbers, 6 is the number of missing objects).
 The second player takes his/her
turn.
 Have them practice many times.
Extensions:
 Write the directions to one
of the games you have learned.
 Write about and describe a favorite strategy
for subtraction and
why it works for you.
 Give instructions for games, individually or in smaller
groups,
providing one step at a time.
 When appropriate, use smaller numbers and gradually
increase.
 Monitor students at the various games to review directions and
rules.
Family Connections
 Teach and play these games with your family.
 Teach a family member these subtraction strategies.
Assessment Plan:
 Have students write and illustrate a story problem.
 Create a short quiz
using the counting back strategy.
 Observe students while they are participating
in the activities.
Bibliography: Research Basis
Isaacs, A., Carroll, W. (1999). Strategies for Basic Fact Instruction. Teaching
Children
Mathematics, 508514.
This article includes research about how facts should be taught,
common strategies used by children to learn facts, the place of practice
in
learning basic facts, a sequence for teaching facts, and how fact
knowledge should be assessed. (Research was conducted at the
University of Chicago School Mathematics Project.)
Author: Utah LessonPlans
Created Date : Sep 29 2005 13:54 PM
