Cogito
Grade 1 Math · Chapter 6 · Lesson 1
Longer Than, Shorter Than
Line them up at the same end first.
10 problems · about 10 minutes · 1.MD.A.1
What this lesson teaches
The child compares two objects directly and describes which is longer or shorter.
- Line up one end before you compare.
- Then look at the other end.
- The one that sticks out further is longer.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
7 problemsReview — True or False to Twenty: Is 13 − 9 = 2 + 2 true?
Answer True. Both are 4.
Why Both sides come to 4.
Review — Missing Numbers to Twenty: 8 + ? = 12
Answer 4
Why 8 + 4 = 12.
Review — Take From Ten in Stories: 11 − 8 = ?
Answer 3
Why 11 − 8 = 2 + 1 = 3.
Review — Taking From Ten: 13 − 9 = ?
Answer 4
Why 13 − 9 = 1 + 3 = 4.
Review — Counting On or Making Ten?: 8 + 2 = ?
Answer 10
Why 8 + 2 = 10.
Review — Start With the Bigger One: 6 + 9 = ?
Answer 15
Why 9 + 6 = 10 + 5 = 15.
Review — Making Ten From Eight: 8 + 5 = ?
Answer 13
Why 8 + 5 = 10 + 3 = 13.
Warm Up
Straightforward practice. Get the method working first.
2 problemsWhy must you line up one end before comparing?
Answer Otherwise you cannot tell which is longer.
Why Lining up the ends is what makes the comparison fair.
A rope is 9 cubes. A string is 6 cubes. How much longer is the rope?
Answer 3 cubes
Why 9 − 6 = 3.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
1 problemTwo Sticks: A red stick is 8 cubes long. A blue stick is 5 cubes. Which is longer?
Answer The red stick.
Why 8 cubes is longer than 5 cubes.