The basic rules of installment sales reporting are pretty straightforward. If you know the basis of property disposed of, and can value the property received on its disposition, then you know what percentage of the sales proceeds are profit, taxable gain. So, each time the taxpayer receives an installment payment of principal, the amount of gain is that percentage applied to the amount of principal received (interest is reported separately, as interest, and of course treated as ordinary income not gain). Starting on page 840 in 19e and page 836 in 20e, we see "Situations in Which Section 453 is Inapplicable." Each student should pick one and provide both a description of, as well as the rationale for, that exception. In your reply posts try to cover anything that wasn't covered in the first round of posts