Border Builders Worksheet
Border Builders
Specialized Math: Perimeter with Regrouping
Name:
Date:
How-To: Find Perimeter with Regrouping
1. Color-Match: Write each side's number in the row with the matching color box.
2. Ones Column: Add the ones. Write the ones digit below, and carry the tens digit up to the yellow Regroup Box!
3. Tens Column: Add the carried number plus all tens digits!
25 in 15 in 25 in 15 in Example
2
Side
T
O
Top
2
5
Right
1
5
Bot
2
5
Left
1
5
Total
8
0
1
The Backyard Garden Plot
Trace the outer borders:
26 ft
18 ft
26 ft
18 ft
Unit: feet (ft)
Write & Solve Here:
Regroup
Tens
Ones
Top
Right
Bot.
Left
Total
=
Perimeter =
feet
Page 1 of 4
Border Builders
Specialized Math: Perimeter with Regrouping
Page 2
2
The Cozy Bedroom Rug
Trace the outer borders:
24 in
17 in
24 in
17 in
Unit: inches (in)
Write & Solve Here:
Regroup
Tens
Ones
Top
Right
Bot.
Left
Total
=
Perimeter =
inches
Page 2 of 4
Border Builders
Specialized Math: Perimeter with Regrouping
Page 3
3
The Painted Art Canvas
Trace the outer borders:
19 cm
13 cm
19 cm
13 cm
Unit: centimeters (cm)
Write & Solve Here:
Regroup
Tens
Ones
Top
Right
Bot.
Left
Total
=
Perimeter =
cm
Page 3 of 4
Border Builders
Specialized Math: Perimeter with Regrouping
Page 4
4
The School Desk Surface
Trace the outer borders:
26 in
16 in
26 in
16 in
Unit: inches (in)
Write & Solve Here:
Regroup
Tens
Ones
Top
Right
Bot.
Left
Total
=
Perimeter =
inches
My Math Builder Checklist:
I matched each number to its colored row.
I carried my regrouped tens up to the yellow box.
I added the carried tens with the other tens.
I double-checked my work.
Page 4 of 4
Border Builders Answer Key
Border Builders KEY
Teacher Answer Key & Teaching Guide
Page 1 of 2
Teacher Note: Guiding Through the Scaffold
This scaffold is designed to bypass working-memory overload by color-matching values to their visual counterparts. If a student gets stuck, ask: "Which border color matches this box?" and point from the shape to the addition row.
1
Problem 1: Backyard Garden Plot
Answer: 88 ft
26 ft 18 ft 26 ft 18 ft
Outer Borders Filled
2
Carried
Top
2
6
Right
1
8
Bot.
2
6
Left
1
8
Total
=
8
8
2
Problem 2: Cozy Bedroom Rug
Answer: 82 in
24 in 17 in 24 in 17 in
Outer Borders Filled
2
Carried
Top
2
4
Right
1
7
Bot.
2
4
Left
1
7
Total
=
8
2
Page 1 of 2
Border Builders KEY
Teacher Answer Key & Teaching Guide
Page 2 of 2
3
Problem 3: Painted Art Canvas
Answer: 64 cm
19 cm 13 cm 19 cm 13 cm
Outer Borders Filled
2
Carried
Top
1
9
Right
1
3
Bot.
1
9
Left
1
3
Total
=
6
4
4
