Active reading just means you're reading something to learn and gain information. You're engaged and determined to understand the text instead of just reading it and letting the information go in one ear and out the other.
In this paragraph, a white puddle is a simile for snow. If the sentence where white puddle is mentioned is this one: Patches of old snow, scattered here and there, looked like white puddles.
Balance your freedom and responsibility by managing your time. After figuring out your class (and/or work, internship, volunteering, etc) schedule, go through your calendar and set aside a specific time just for studying and homework.
A poetic stanza that has four lines