Addition Word Problems

1Summary 重點摘要

When a story says put together, use addition.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Step 1: Read twiceFor an addition word problem, read the question twice: the first time for the whole story, and the second time to circle the numbers and key words. Example: Elder Sister has 3 sweets and Younger Sister has 5 sweets; how many sweets altogether? After reading we know the numbers are 3 and 5, and the question asks 'altogether'. Why read twice? The first reading only holds the story, and the second gathers all the numbers. A common mistake is rushing to write the sum after one reading, dropping a number, and then the answer goes wrong.
2. Step 2: Circle key wordsKey words in the question tell us which method to use; 'altogether', 'in all' and 'together' all point to addition, meaning the two or more groups are joined and counted as one. Example: in 'Elder Sister has 3 sweets and Younger Sister has 5 sweets; how many altogether', the word 'altogether' means the 3 sweets and the 5 sweets are combined. Circling the key words keeps the method right. A common mistake is adding as soon as numbers appear, without noticing that the question actually asks 'how many are left', using addition where subtraction was needed.
3. Step 3: Write the sumAfter deciding on addition, write the sum down completely instead of working it out only in the head. Example: write 3 + 5 = ?; the written sum shows clearly which numbers are being added and gives a basis for checking later. Write the numbers and signs neatly, and never leave out the plus sign or the equals sign. A common mistake is panicking when the two numbers are written in a different order, yet addition allows swapping, and 3 + 5 is the same as 5 + 3; what must be avoided is a missing number or a missing plus sign.
4. Step 4: Work it outAddition can be worked out by counting on: start from the bigger number and count on as many steps as the smaller number. Example: for 3 + 5, count on 3 steps from 5: 6, 7, 8, so 3 + 5 = 8; or draw 3 circles and 5 circles and count them all together. Point with a finger while counting and bend one finger for each number, then check once more. A common mistake is counting the starting number as the first step, for example beginning at 5 and counting the 5 itself, which adds one extra and gives 9.
5. Step 5: Answer in a sentenceAfter finding the answer, write a full answer sentence that follows the way the question asks, and remember the unit. Example: when the question asks 'how many sweets altogether', write 'There are 8 sweets altogether', with the number 8 and the unit 'sweets'. Without the unit, nobody knows whether the 8 means sweets, people or something else, and the answer is not complete. A common mistake is writing only the bare number 8 and treating it as done, or writing the wrong unit, for example 'birds' for sweets; match the answer words to the things in the question.
6. Step 6: CheckChecking means using the opposite operation: check addition by subtraction, taking one addend away from the answer, and the result should equal the other addend. Example: for 3 + 5 = 8, use 8 - 5 = 3; the result matches the 3 from the question, so nothing went wrong, and 8 - 3 = 5 can confirm it once more. Spending a little time on checking after a word problem makes the answer reliable. A common mistake is glancing at the work and passing it without really doing the subtraction; only by working it out can real errors be found.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• Read the problem twice; find the numbers.
• 'Altogether', 'in all', 'more' usually mean add.
• Write the sum: 3 + 5 = 8.
• Answers need units.
• Check addition with subtraction.