Something I feel is poorly understood is the rate of doubling at different percentage growth rates and real vs. nominal growth. 3% will double in ~24 years, 7% in ~10 years, 10% in 7 years, etc. My mother was so happy to lock in a 3% lifetime annuity since it was "guaranteed", while we had 3.8% inflation average over the last 100 years - it still hurts.

I'd also recommend going over what an amortization schedule schedule is specifically in regards to a mortgage, to see the total cost of a loan vs. just the principal.