Grade 2, Module 10
Core Focus
• Using place value to add two- and three-digit numbers
• Identifying polyhedrons and pyramids
• Investigating and drawing 3D objects
Addition
• Students extend their addition strategies to three-digit numbers. They may “count on” (e.g.
see 334 + 30 and think 334 + 10 + 10 + 10) or use “place value” (e.g. see 334 + 253 and
think 334 + 200 + 50 + 3, or 3 hundreds + 2 hundreds + 3 tens + 5 tens + 4 ones + 3 ones).
10.2
Adding Two- and Three-Digit Numbers
A school play is being held in the gym.
Last week, 457 tickets were sold. Then an extra 32 tickets were sold yesterday.
How could you figure out the total number of tickets that have been sold?
451
452 453 454 455 456 457 458 459 460
461 462 463 464 465 466 467 468 469 470
471
472 473 474 475 476 477 478 479 480
I could start with 457
and add the tens, then
the ones like this.
481 482 483 484 485 486 487 488 489 490
491
492 493 494 495 496 497 498 499 500
457 + 30 is 487
487 + 2 is 489
Jackson used blocks to help figure out the total.
How many hundreds are there in total? How many tens? How many ones?
In this
lesson,
strategies
tototal.
add two-digit
1. students
Use the chart examine
above to help you
figure out each
Step Up
Then write the totals.
numbers to three-digit
numbers that do not involve bridging.
a. 451 + 23 =
b. 466 + 12 =
• Continue to practice the
“make-ten” strategy with
your child (children see
27 + 4 and think 27 + 3
equals 30 and one more is
31). This strategy helps your
child when using the number
line to add two- and threedigit numbers.
• Ask your child to count on
by tens or hundreds from
any two-digit or three-digit
number. Challenge them to
count past 100. E.g. starting at
74 and counting on by tens is
“74, 84, 94, 104, 114, 124.”
c. 31 + 453 =
© ORIGO Education.
• It is important that students have extended experience in composing numbers
d. 464 + 35 =
e. 455 + 43 =
f. 482 + 16 =
because thinking about regrouping 10 tens for 1 hundred, or 10 ones for 1 ten, is
226 experience for adding numbers that require regrouping.
important background
ORIGO Stepping Stones 2 • 10.2
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10.4
Ideas for Home
Composing Three-Digit Numbers
Look at this picture of blocks.
What number does it show?
How do you know?
What could you do with the ones blocks to make 4 tens blocks
and keep the total the same?
Glossary
Bridging is composing
across place values.
E.g. adding 18 and 5 is
bridging from ones to tens.
Eight ones and five ones
is 13 ones, which is also
one ten and three ones.
7 hundreds, 16 tens, and 2 ones
is the same as
862
In this
students work with regrouping numbers
Look lesson,
at this picture.
where a ten or a hundred has to be composed.
• Students solve addition problems that require regrouping. In the problem from the
lesson on the next page, students add 193 and 24. Adding 9 tens and 2 tens gives
What could you do with the blocks to make 2 hundreds blocks
and keep the
total the same?
11 tens. Students regroup
these
11 tens for 1 hundred and 1 ten so 193 + 24 = 217.
How many tens blocks would you have?
How many ones blocks would there be?
Does the total change?
© ORIGO Education.
© ORIGO Education.
I could trade 10 ones blocks for 1 tens block.
That makes 4 tens blocks and the total does not change.
1
Grade 2, Module 10
• Number charts, base-10 blocks, and number lines are used as aids to make the
thinking visible and help students connect their strategies to the sizes of the
numbers involved.
Adding Two- and Three-Digit Numbers (with Bridging)
10.6
Look at these pictures of blocks.
What numbers do they show?
How could you figure out the total?
Ideas for Home
• With your child, look for
examples of polyhedrons of
various types, including some
pyramids, in your home and
community. Some examples
are dice and shoe boxes.
Leticia added on a number line like this.
+20
193
190
+4
200
210
213
217
220
Glossary
A polyhedron is any 3D
object that has only flat
faces (e.g. a cube).
230
Draw jumps on this number line to show another way to find the total.
In this lesson, students use a place value strategy to
add two- and three-digit numbers that involve bridging
across190one place.
200
210
220
230
• Students use a strategy of their
choice to solve any addition problem with
1. Write the number of hundreds, tens, and ones. Then write an
Step Up
sentence to show the total. You can use blocks to help.
three-digit numbers. Studentsaddition
write
number sentences to show their thinking
a.
354 + 28
b.
286 + 32
and compare their strategies with each other.
10.8
There are
hundreds.
There are
hundreds.
There are
tens.
There are
tens.
Consolidating Addition with Three-Digit Numbers
+
=
umb
rella
$18
234
tent
+
$43 +
5
cam
p ch
air
$
23
© ORIGO Education.
+
$184 d
edge = where two surfaces
meet
vertex = where edges meet
are
There
ones.
ones.
Nick’s There
family is
buying some
things for a vacation. What
doare
you think they
will be doing?
fishin
g ro
face = any flat (not curved)
surface of a 3D object
=
edge
vertex
ORIGO Stepping Stones 2 • 10.6
070415
edge
How could you figure out the total cost of the tent and the chair?
edge
What number sentences could you write to show your thinking?
Tristan added the places like this:
Keisha counted on the
places like this.
400 + 0 = 400
30 + 20 = 50
5+3=8
400 + 50 + 8 = 458
435 + 20 = 455
455 + 3 = 458
Which method would you use to add numbers like this? Why?
1. Figure out the total cost of each pair of items. You can use blocks
Step Up
draw number lines
on a spare sheet
paper to help. Thenthey
write
In this
lesson,or students
practice
theof strategies
number sentences to show your thinking.
havea. used for adding one-, two-,
and
three-digit
b.
rod and umbrella
numbersfishing
to three-digit
numbers. tent and fishing rod
Geometry: 3D Objects
© ORIGO Education.
• Students learn new vocabulary related to 3D objects such as face, edge, vertex,
polyhedron, and pyramid. Students use these new words to describe features
Total
Total
of polyhedrons and sort a variety of 3D objects.
238
ORIGO Stepping Stones 2 • 10.8
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• Students practice a simple method for drawing prisms (shapes like toothpaste
boxes and cereal boxes).
10.9
Identifying Polyhedrons
© ORIGO Education.
What are some things that you know about 3D objects?
All 3D objects have surfaces.
Some objects have a flat surface.
A flat surface is called a face.
c u r ve d
A 3D object with all flat faces is a polyhedron.
flat
Look at the 3D objects at the top of the page.
Which objects are polyhedrons? How do you know?
1. Mika
was asked to
shadethe
one face
gray“polyhedron”
on each
In this
lesson,
students
use
term
to
Step Up
of these objects. Shade one
to describe his answer.
describe
3D
objects
that
have
only
fl
at
surfaces.
a.
b.
He shaded a face.
He did not shade a face.
He shaded a face.
2