Explain why a sexual reproduction results in offspring with identical DNA/genetic information and sexual reproduction results in offspring will be varied DNA/genetic information.

In asexual reproduction, you are essentially producing clones of the parent.  There is no genetic variation between parent and offspring - think of mitosis.

In sexual reproduction, you have several chances for genetic variation.  The first occurs in meiosis 1, when homologous pairs line up and crossing over occurs.  Then in meiosis 2, different combinations of chromosomes (some from mother, some from father) could end up in the gamete cells.  Finally, when the gametes (egg and sperm/spore) come together in fertilization, that represents a brand new combination of chromosomes, and therefore alleles, than either of the parents had.