- Comparing numbers (how much larger, how much smaller)
- How far apart
- Removing from a total or from a group
Addition was used for combining numbers together. In what type of situation would you use subtraction?
Interactive popup. Assistance may be required.
What hints might you see in a word problem to indicate that you would use subtraction?
Interactive popup. Assistance may be required.
Read the following word problem and answer the questions below using your notes. If you need a hint, you can hover your cursor over the word 'hint.'
The words "how much less" were a clue that you should use subtraction in this problem. Brainstorm a list of other words that could be used in a word problem to indicate using subtraction. Record the list in your notes.
Interactive popup. Assistance may be required. Difference, less, decrease, loss, subtracted from, how much less, how much more, how much larger, how much smaller, decrease, reduce, take away, minus.
Read the following problem and answer the questions below. Record your answers using your notes.
You and your lab partner are taking temperature measurements during a science lab. You put a thermometer in a beaker of hot water and record the temperature every minute as it cools. Part of the data chart is shown below:
Time (minutes) |
Temperature (°C) |
0 |
75 |
1 |
73 |
2 |
70 |
3 |
68 |
4 |
65 |
5 |
62 |
What is the difference in temperature between the first reading (at time = 0 minutes) and the last reading (at time = 5 minutes)?
Which mathematical operation should you use to solve this problem?
Interactive popup. Assistance may be required. Subtraction
How did you know which operation to use?
Interactive popup. Assistance may be required. The problem used the phrase, "What is the difference in temperature" that means we are finding how much larger or smaller one number is than another.
Which two numbers should you use from the table?
Interactive popup. Assistance may be required. 75°C and 62°C.
Why did you select those numbers?
Interactive popup. Assistance may be required. They are the temperatures that go with the times given in the problem.
Write an equation that you could use to solve for the difference in temperature, T.
Interactive popup. Assistance may be required. T = 75 – 62
What was the difference in temperature?
Interactive popup. Assistance may be required. T = 13. The difference in temperature is 13°C.