Cogito
Grade 2 Math · Chapter 6 · Lesson 6
Filling a Rectangle With Squares
Rows and columns again, this time in shapes.
10 problems · about 12 minutes · 2.G.A.2
What this lesson teaches
The child partitions a rectangle into rows and columns of same-size squares and counts them.
- A rectangle fills with same-size squares in rows and columns.
- Count one row, then count the rows.
- It is the same idea as an array of counters.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Writing the Equation: 3 rows of 4. What is the total?
Answer 12
Why 3 rows of 4 is 12.
Review — Rows and Columns: 3 rows of 5. How many in all?
Answer 15
Why 3 rows of 5 is 15.
Review — Equal Groups: 5 groups of 4. How many in all?
Answer 20
Why 4 + 4 + 4 + 4 + 4 = 20.
Warm Up
Straightforward practice. Get the method working first.
3 problems2 rows of 5 squares. How many squares?
Answer 10
Why 2 rows of 5 is 10 squares.
How should you count the squares?
Answer Count one row, then count the rows.
Why Counting by rows is the whole advantage of an array.
4 rows of 4 squares. How many squares?
Answer 16
Why 4 four times.
Build It Up
The same ideas with more to keep track of.
1 problem3 rows of 5 squares. How many squares?
Answer 15
Why 5 + 5 + 5.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsDo the squares have to be the same size?
Answer Yes. Otherwise it is not fair.
Why Think about counting them.
The Tiled Floor: A floor has 5 rows of 4 tiles. How many tiles are there?
Answer 20 tiles
Why 5 rows of 4 is 20 tiles.
The Window: A window has 2 rows of 3 panes. How many panes?
Answer 6 panes
Why 2 rows of 3 is 6 panes.