To show that Derek succeeded in using the dream machine to complete his his project.
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Because if some people are quiet they could be holding in something serious or if you are in class and you are always quiet your peers and teachers are going to wonder if something is bothering you
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5 minutes all the way up to fifteen is 10 minutes 15 to 25 is ten more then 25 to 35 is ten more so in all about so it takes karla about 30 minutes