Mathematical Emphasis
Investigation 1: Comparisons with Record Num-
bers
•
Comparing two numbers and developing strategies
for determining their difference
•
Developing ways of getting close to 100 by com-
bining numbers
•
Using landmark numbers (multiples of 10 and 100)
to compare two quantities
Investigation 2: How Much Heavier or Lighter?
•
Developing conjectures about and making com-
parisons of how things change over time
•
Comparing weights with a pan balance
•
Finding how far a number is from the next multiple
of 10 or multiple of 100
Investigation 3: Adding with Money, Inches, and
Time
•
Solving addition problems with multiple addends
and keeping track of the steps
•
Developing a repertoire of addition strategies that
rely on students’ number sense and understanding
of number relationships
•
Recognizing and using standard addition notation
while using approaches based on sound number
operation sense.
•
Exploring number relationships and using impor-
tant equivalencies in time, money and linear meas-
ure
•
Using estimation to make good approximations
Investigation 4: Working with Hundreds
•
Developing and communicating strategies for combining
and comparing quantities in the hundreds and thou-
sands
•
Using standard notation to record
•
Using multiples of 100 as landmarks
•
Collecting, recording and graphing data
Investigation 5: Calendar Comparisons
•
Exploring the mathematical characteristics of the calen-
dar and using them to solve problems
Grade 3
Tips for Helping at Home
•
Questions to ask:
What is it that you don’t understand (have
the student be specific)?
What about putting things in order?
Could you try it with simpler numbers?
Can you guess and check?
Does this make sense?
What can you do to explain your answer to
show others what you are thinking?
Does your answer seem reasonable?
•
When your child has an assignment to do at
home - such as collecting data about the ages of
pets and oldest relatives - offer your help, and
ask your child about what he or she is doing in
class.
•
Ask your child to describe any of the homework
problems and tell you about the strategy used to
solve it. Communication is an important part of
mathematics, and students need to describe their
strategies through talking, writing, drawing, or
using concrete objects. You can be an important
audience.
•
You can also
share your own
ideas. At one
point, we will
work on the
mathematics of
“party planning.”
You might explain how you would figure out how
to fit a number of different activities into a two-
hour block of time.
Websites
http://cms.everett.k12.wa.us/math/Third Grade
Addition and
Subtraction
Vocabulary
representation - expressing mathematical
problems in a variety of forms.
pictures, numbers, words, or models
4 + 4 = 8
There were four birds on a wire. Four more
joined them. Eight birds were now on the wire.
standard notation -
addition 48 + 18 = 66
subtraction 32 - 13 = 19
Glossary
http://www.amathsdictionaryforkids.com/
Game
Close to 100
Materials:
One deck of Numeral Cards
Close to 100 Score Sheet per player
Players:
1, 2, or 3
How to Play:
1. Deal out six Numeral Cards to each player.
2. Use any four of your cards to make two num-
bers. For example:6 and 5 could make 65 or 56.
Wild cards can be used as any numeral. Try to
make numbers that, when added, give you a
total that is close to 100.
3. Write these two numbers and their total on the
Close to 100 Score Sheet. For example: 42 + 56
= 98.
4. Find your score. Your score is the difference
between your total and 100. For example: If your
total is 98, your score is 2. If your total is 105,
your score is 5.
5. Put the cards you used in a discard pile. Keep
two cards you didn’t use for the next round.
6. For the next round, deal four new cards to each
player. Make more numbers that come close to
100. When you run out of cards, mix up the dis-
card pile and use those cards again.
7. Five rounds make one game. Total your scores
for the five rounds. LOWEST score wins!
Score Sheet example:
Score
Round 1: ___ ___ + ___ ___ = ______
_______
Round 2: ___ ___ + ___ ___ = ______
_______
Round 3: ___ ___ + ___ ___ = ______
_______
Round 4: ___ ___ + ___ ___ = ______
_______
Round 5: ___ ___ + ___ ___ = ______
_______
Total Score ________
About the Mathematics In This Unit
During the next few weeks in math, our class
will be working on addition and subtraction.
We’ll be focusing on interesting and real prob-
lems that involve combining and comparing two
or more amounts.
Students will be learning about many different
ways to solve addition and subtraction prob-
lems. Students will be encourages to develop
more than one way to solve a problem and to
use methods that are based on understanding
numbers and their relationships.
Some of these methods may not be the ones
you learned in school, but you may recognize
some of them as methods you use in your daily
life. We encourage students to develop strate-
gies that make sense to them, that they can use
easily and flexibly. For example, one of the first
things we will do is compare the age of your
family’s oldest relative with the age of the oldest
person on record (120 years old). Suppose your
oldest relative is 83 years old. Your child might
find the answer by seeing how many years you
must add on to get from 83 to 120. Add 7 to get
to 90, 10 more to get to 100, 20 more to get to
120. Another approach would be to subtract 80
from 120 to get 40 then subtract 3 more to get
37.
The point is for chil-
dren to find useful
and meaningful ways
of putting together
and taking apart
numbers.
Mokros, J. Investigations in Number, Data, and Space: Combining
and Comparing. Dale Seymour Publications, 1998.
