Norma jarred 12 liters of jam after 3 days. How much jam did Norma jar if she spent 6 days making jam? Solve using unit rates.

If Norma jarred 12 liters of jam after 3 days, then she jars 12/3 = <<12/3=4>>4 liters of jam per day.

Since she spent 6 days making jam, Norma jarred a total of 4 x 6 = <<4*6=24>>24 liters of jam. Answer: \boxed{24}.