One of my students asked me to explain the difference between "within" and "during" in the context of time expressions.
I could not find an exercise for him to practice this and so I made up my own brief one - see below. Any feedback from teachers and/or students would be welcome. Thanks.
Within / during + time expression<o:p></o:p>
Within and during are both used with time expressions.<o:p></o:p>
During + period or thing that extends over time but the precise duration is not defined e.g. during the night, during the journey<o:p></o:p>
Within + maximum specific duration e.g. within 3 weeks, within a year<o:p></o:p>
Choose the more natural option – within or during – to complete the following sentences. In one of the sentences, either option is equally natural, in my opinion.<o:p></o:p>
1.  the film we watched at the cinema, my mobile phone rang. It was so embarrassing.<o:p></o:p>
2. I gave my baby son a new book but  48 hours, he had destroyed it.<o:p></o:p>
3.  its maiden voyage, the Titanic hit an iceberg.<o:p></o:p>
4. Don’t disturb me now. I am expecting a call  the next hour.<o:p></o:p>
5. You must return the library book  3 weeks or face a fine.<o:p></o:p>
Technically both words could be used in any of these examples, however one or the other sounds more natural, and is more often used over the other.
In conclusion, I would tell your student that, "While both mean the same thing, use the word 'during' when given an indefinite timeline and use 'within' when specified the time." For example, in #2, the sentence context was 24 hours, so use "within" while in sentence #3, you said during the voyage, but didn't state how long the voyage was. Refer to sentence #4 and #5 for further explanation. #4 (The next hour) #5 (3 Weeks). #1 (The film). But how long was the film? It was not specified, so use "During." Hope this helps!