2nd Grade Math Notes
Compare/Represent Numbers
Missing Value or Part-Part-Whole
Numbers can be expressed in four formats.
A problem is provided. There will be a missing
Standard Form : 1,942
value, or part, not known. Use the information to
Word Form: one thousand nine hundred forty two
find the missing value.
whole
Expanded Form: 1,000 + 900 + 40 + 2
Base Ten:
part
25
part
5
?
part + part = whole
xx
* If you are missing a part you will subtract. If
you are missing the whole you will add.
Example:
There were 25 cats outside and 5 cats ran inside.
How many cats are outside?
25 - 5 = ?
Rounding
Symbols
= equals
2+4=6
≠ not equal
6+2≠5-3
If the number ends with a 1, 2, 3 or 4 you round
down.
If the number ends with a 5, 6, 7, 8 or 9 round
> greater than
6>4
<
less than
2<7
up.
Example:
Vocabulary
~ Break apart - express numbers in expanded
notation
example: 342 = 300 + 40 + 2
17
20
22
20
53
50
57
60
2nd Grade Math Notes
Angles
s
te
n
on
es
s
re
d
nd
,
hu
th
ou
sa
nd
s
Place Value
When a digit changes this makes the value
change.
Example:
2,423
~ Change the 4 to a 6.
~ How does this change the number?
~ The value was increased by 200 (not 2).
Solid Figures
Solid Figures
Parts of Solid
Examples of Solid Figures
2nd Grade Math Notes
Polygons
Attributes of Shapes
(a closed figure with straight sides)
a common characteristic that makes a shape part
of a group
triangle
Ex. all triangles have three sides
Polygons can be used to create other polygons.
quadrilateral
Think: Flip, Turn and Cut
pentagon
hexagon
octagon
Properties
Properties
Commutative Property - you can add numbers in
Associative Property - changing the grouping of
any order and the sum will be the same
three or more addend does not change the sum
8 + 4 = 12
4 + 8 = 12
8
+
(4
+
2)
8
+
(
6
)
Identity Property - when you add zero to a
IS THE SAME AS
number, the sum will be that number
0+9=9
9+0=9
(8
(
+
12
4)
+
2
)
+
2
2nd Grade Math Notes
Problem Solving
Touch Math Touchpoints
Key Words
Add
Subtract
sum
difference
in all
are left
total
subtract
and
greater
how many
more
combined
less
both
fewer
altogether
gave away
are not
Joey caught 25 fish. Sam caught 17 fish. How
many more fish did Joey catch?
Thought
Information
25, 17
Plan
25 - 17 =
Solution
□
8
www.touchmath.com
Counting On Using Touchpoints
Counting Back Using Touchpoints
say the bigger number and count on with the
say the bigger number and count back with the
smaller number
smaller number
3
+7
10
"7
8 9 10"
9
-5
4
"9
8 7 6 5 4"
2nd Grade Math Notes
Addition with Regrouping
Standard Form
Base Ten
+
8
1
5
4
3
Standard Form
x x x
1
2
Subtraction with Regrouping
l l
2
x x x
-
x x
3
4
2
7
x x x x x
x x x x x
l l l x x x x
-
x
llll
Place Value
14
7
x x x
l
+
Base Ten
2
7
xxxx
x x x
xxx
Expanded Form
Place Value
Expanded Form
2 tens 14 ones
20 + 14
2 tens + 8 ones
20 + 8
3 tens 4 ones
30 + 4
1 ten + 5 ones
10 + 5
- 2 tens 7 ones
- 20 + 7
3 tens and 13
30 + 10 + 3
7 ones
7
3 tens + 1 ten + 3 ones
40 + 3
4 tens and 3 ones
Addition and Subtraction
Math Websites
Addition and Subtraction are inverse (opposite) http://acworthelem.typepad.com/ms_myers_math_cla
operations so they can be used to check each
ss/2nd.html
other.
1
-
18
2
8
1
9
http://www.aplusmath.com/games/
1
9
+
9
1
9
2
8
http://www.aaamath.com/
http://www.coolmath.com/
Addition with Regrouping
t take 10 ones to the tens place
http://www.hbschool.com/glossary/math2/index2.htm
l
Subtraction with Regrouping
t take 1 ten to the ones place
http://www.toonuniversity.com/flash.asp?err=503&en
gine=15
http://www.funbrain.com/numbers.html
2nd Grade Math Notes
Data
Data
Use a tally chart to create various graphs.
Picture Graph
Favorite Foods
tacos
tacos
hamburgers
hamburgers
hot dogs
hot dogs
pizza
pizza
Pictograph
Bar Graph
Favorite Foods
tacos
Favorite Food
hamburgers
10
hot dogs
5
pizza
0
tacos
hamburgers
hot dogs
How many more students like pizza better than tacos?
Data
Venn Diagram
A
B
= 2 students
pizza
C
Describe the figures located in section C.
A.
shapes with three side
B.
shapes with three sides and right angles
C.
shapes with right angles
How many students chose hamburgers as their favorite
food?