Integers Introduction — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
The integer +4 is to the left of -4 on a number line.
Corrected: The integer +4 is to the right of -4 on a number line.
All positive integers appear to the right of zero and all negatives to the left.
2. Fix the sentence:
A thermometer showing -12 degrees is hot weather.
Corrected: A thermometer showing -12 degrees is very cold weather.
Negative temperatures show cold conditions far below the freezing point of water.
3. Fix the sentence:
The integer 9 has a smaller value than 0.
Corrected: The integer 9 has a greater value than 0.
Any positive integer is greater than zero on a standard number line.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. The integer that comes right before 1 on a number line is 0.
One unit left of 1 is exactly zero on the integer number line.
2. If you owe a friend twelve dollars, your balance can be shown as -12.
Owing money is recorded as a negative integer because value is below zero.
3. The opposite integer of -15 is 15.
The opposite of any negative integer is the matching positive integer.
4. A thermometer reads three degrees above zero, written as 3.
Positive integers are written without a sign or with an optional plus sign.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Describe how a vertical number line is different from a horizontal one.
Sample answer: A vertical number line goes up and down, with positives going up and negatives going down from zero in the middle.
Vertical lines like thermometers show positives upward and negatives downward from zero.
2. What does it mean if the temperature drops from 5 to -2 degrees?
Sample answer: It cooled down by seven degrees, crossing zero, so the air is now below freezing instead of above.
Crossing zero on a thermometer means moving from warm conditions to colder conditions.