Hi Tommo,
That's a very good suggestion! We'll keep it in mind for new lesson creations
Meanwhile, you can find a short briefing of the use of
de shíhou in our Elementary Lesson #40, please check it out!

(
http://www.chineseclass101.com/2009/10/ ... -security/)
Generally speaking,
de shíhou always go behind the action/situaion; while
dāng always go in front.
For examples:
吃饭
的时候不要说话。
chīfàn de shíhou bùyào shuōhuà. (Don't talk while eating.)
当我听到这个消息,我哭了。
dāng wǒ tīng dào zhège xiāoxi, wǒ kūle.(When I heard the news, I cried.)
Or a combination of both to emphasize the timing:
当你过马路
的时候要当心汽车。
dāng nǐ guò mǎlù de shíhou yào dāngxīn qìchē. (Watch out for cars when you cross the street.)
Cheers,
Olivia
Team ChineseClass101.com