Plural Nouns worksheet from Tree Valley Academy, teaching rules for forming plurals ending in "o" and irregular plural nouns.

Problem Overview:

The task involves converting singular nouns that end in "O" into their plural forms. The rules provided are as follows:

1. If the letter before "O" is a consonant, add "ES" to make it plural.
- Example: mosquito → mosquitoes
2. If the letter before "O" is a vowel, add "S" to make it plural.
3. Exceptions: Words like "photo," "piano," and other music words (e.g., "cello") only need an "S."

Additionally, there is a section on irregular plural nouns, which do not follow regular rules and must be memorized.

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Solution:

#### Part 1: Plural Nouns Ending in "O"

We will apply the rules to each word:

1. video
- Letter before "O": "E" (vowel)
- Add "S": videos

2. hero
- Letter before "O": "R" (consonant)
- Add "ES": heroes

3. tomato
- Letter before "O": "A" (vowel)
- Add "S": tomatoes

4. kangaroo
- Letter before "O": "U" (vowel)
- Add "S": kangaroos

5. ratio
- Letter before "O": "I" (vowel)
- Add "S": ratios

6. photo
- Exception: Only add "S"
- Result: photos

7. echo
- Letter before "O": "C" (consonant)
- Add "ES": echoes

8. zoo
- Letter before "O": "O" (vowel)
- Add "S": zoos

9. radio
- Letter before "O": "I" (vowel)
- Add "S": radios

10. piano
- Exception: Only add "S"
- Result: pianos

11. stereo
- Letter before "O": "E" (vowel)
- Add "S": stereos

12. igloo
- Letter before "O": "L" (consonant)
- Add "ES": igloos

13. trio
- Letter before "O": "I" (vowel)
- Add "S": trios

14. potato
- Letter before "O": "A" (vowel)
- Add "S": potatoes

15. cello
- Exception: Only add "S"
- Result: cellos

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#### Final Answers for Part 1:
- video → videos
- hero → heroes
- tomato → tomatoes
- kangaroo → kangaroos
- ratio → ratios
- photo → photos
- echo → echoes
- zoo → zoos
- radio → radios
- piano → pianos
- stereo → stereos
- igloo → igloos
- trio → trios
- potato → potatoes
- cello → cellos

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#### Part 2: Irregular Plural Nouns

This section lists nouns that do not follow regular pluralization rules. These must be memorized. The table already provides the correct plural forms for each noun.

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Final Answer:

\boxed{
\begin{array}{lll}
\text{video} & \rightarrow & \text{videos} \\
\text{hero} & \rightarrow & \text{heroes} \\
\text{tomato} & \rightarrow & \text{tomatoes} \\
\text{kangaroo} & \rightarrow & \text{kangaroos} \\
\text{ratio} & \rightarrow & \text{ratios} \\
\text{photo} & \rightarrow & \text{photos} \\
\text{echo} & \rightarrow & \text{echoes} \\
\text{zoo} & \rightarrow & \text{zoos} \\
\text{radio} & \rightarrow & \text{radios} \\
\text{piano} & \rightarrow & \text{pianos} \\
\text{stereo} & \rightarrow & \text{stereos} \\
\text{igloo} & \rightarrow & \text{igloos} \\
\text{trio} & \rightarrow & \text{trios} \\
\text{potato} & \rightarrow & \text{potatoes} \\
\text{cello} & \rightarrow & \text{cellos} \\
\end{array}
}