First we practice writing fractions as decimals and vice versa (up to 3 decimal digits). Then I show an easy way to compare decimals: you can write the decimals in a place value chart or table, where it is easy to compare them place by place.
Lastly we do a few practice problems comparing decimals. Be sure to avoid the common student misconception where students think that the part to the right of the decimal point is some kind of "number" in itself. Such students could say that 9.114 is greater than 9.4, thinking that 114 is greater than 4.
Add & subtract decimals using mental math — video lesson
Math Mammoth Decimals 2 — downloadable worktext