...One is to make the idea more concrete and less abstract. A student may not understand why 0.3 is greater than 0.25, but they know why three dimes are worth more than two dimes and a nickel. Another is to present a simpler problem with the same concept, such as posing 1/3 + 1/4 to a student who answers 7/12 + 4/5 = 11/17. (read more)