During prophase I the nuclear membrane disappears, the chromosomes become visible, the meiotic spindle forms, and the centrioles move to opposite poles of the nucleus.

11.2: Activity: Crossing over
11.2: Activity: Crossing over, Discovery Biology 3rd Edition, W.W. Norton Company, "Review the process of crossing over, and its effects."
http://nortonbooks.com/college/biology/animations/...
Chromosomes Crossing Over - Linked Genes
Chromosomes Crossing Over - Linked Genes, Brightstorm Science Videos, Video length: 07:19.
http://www.brightstorm.com/science/biology/mendeli...
In biology, what does "crossing over" mean?
In biology, what does "crossing over" mean?, Yahoo! Answers, Visit the website for several answers.
http://answers.yahoo.com/question/index...
Meiosis I: Prophase I
Meiosis I: Prophase I, Prentice Hall BioCoach Activity, Text and animation.
http://www.phschool.com/science/biology_place/bioc...
Prophase I
Prophase I, BiologyOnline.org, A definition of prophase I.
http://www.biology-online.org/dictionary/Prophase_...
Prophase I
Prophase I, Online Biology Directory, Macroevolution.net, Text and illustrations.
http://www.macroevolution.net/prophase-i.html