Worksheet for learning word formation by adding the suffix "-ger" to base words.

The task in the image involves completing a table by adding the suffix -er to each given word and determining whether the resulting word is a real English word. The goal is to identify which words remain valid after adding the suffix.

Steps to Solve:

1. Understand the Task: For each word in the left column, add the suffix -er to it.
2. Check Validity: Determine if the new word formed is a valid English word.
3. Mark the Result: In the rightmost column, write "yes" if the new word is valid, or "no" if it is not.

Solution:

#### Table Completion:
| Word | New Word (+ -er) | Valid? |
|-----------|-------------------|--------|
| finger | fingerer | no |
| pencil | penciler | no |
| napkin | napkiner | no |
| sister | sisterer | no |
| number | numberer | yes |
| system | systemer | no |
| cannot | cannoter | no |
| center | centerer | yes |
| window | windower | yes |
| winter | winterer | yes |

Explanation for Each Word:

1. finger → fingerer: Not a valid English word.
2. pencil → penciler: Not a valid English word.
3. napkin → napkiner: Not a valid English word.
4. sister → sisterer: Not a valid English word.
5. number → numberer: A valid English word (referring to someone who numbers things).
6. system → systemer: Not a valid English word.
7. cannot → cannoter: Not a valid English word.
8. center → centerer: A valid English word (someone who centers something).
9. window → windower: A valid English word (someone who installs windows).
10. winter → winterer: A valid English word (someone who winters somewhere).

Final Answer:

$$
\boxed{
\begin{array}{|c|c|c|}
\hline
\text{Word} & \text{New Word (+ -er)} & \text{Valid?} \\
\hline
\text{finger} & \text{fingerer} & \text{no} \\
\text{pencil} & \text{penciler} & \text{no} \\
\text{napkin} & \text{napkiner} & \text{no} \\
\text{sister} & \text{sisterer} & \text{no} \\
\text{number} & \text{numberer} & \text{yes} \\
\text{system} & \text{systemer} & \text{no} \\
\text{cannot} & \text{cannoter} & \text{no} \\
\text{center} & \text{centerer} & \text{yes} \\
\text{window} & \text{windower} & \text{yes} \\
\text{winter} & \text{winterer} & \text{yes} \\
\hline
\end{array}
}
$$