I have been working with metric conversions with my 6th graders. I have found that using the pnuemonic phrase "Karen's Hair Dried but didn't curl much" is useful in showing how to convert in metrics. The first letter of each word stands for a unit in metrics...K - kilo; H - Hecto; D - Deca; b - base (meter, liter, or gram); d - deci; c - centi; and m - milli. Students look to see what unit they are starting at and what unit they are moving to. They count as they move from one to the other and note the direction they are moving. This tells them how many places to move the decimal and which way to move it. They really catch on fast. Afterwards I explain to them how they were actually multiplying or dividing by a power of 10. This worked well because they already knew that when you multply by a power of 10 you move the decimal to the right and when you divide by a power of 10 you move the decimal to the left. They remember this by using the following: MR. DL (multiply right/divide left).