Which number is greater 0.100 or 0.101?trying to teach how to put decimals in order of greater or lessor

A simple way to assess which number is greater is to move
the decimal point to the right as far as you can in both numbers (as long as the decimal
is moved an equal number of places in each).

Doing this for
0.100 would give you 100.  Doing this for .101 would give you 101.  It is easy for a
student to tell which of those numbers is the larger one, and the reason why is exactly
the same.  If all you are trying to do is teach them how to put them in order, that is
one easy and sure fire way they can use every time.

I also
have found it is easier when students say the whole decimal out loud.  One hundred
thousandths, and one hundred one thousandths.  What usually confuses them is the visual,
and saying it out loud gives them another way to see it.