Make it simple, tell them that after the flop with the turn still to come, take their number of outs and multiply it by 4. That will roughly give them their percentage of making their hand ( add 2% and it may be a lil more accurate). After the turn with the river still to come, take their number of outs and multiply it by 2. That will roughly give them their percentage of now making their hand ( add 1% and it may be a lil more accurate).
For example... if after the flop you have four to a flush ( you need one more to make your flush) there are 9 more of that suit to make your flush.
9 X 4 = 36
You are roughly 36% (or possibly 38%) to make your flush.
Lets continue with hand and assume ( Yeah yeah, I know what happens when you assume) the turn is a brick and you still have four to a flush.You still have 9 outs.
9 X 2 = 18
You are roughly 18% ( or possibly 19%) to make your flush.
There are probably much more accurate ways of calculating your odds and outs but this one is simple and it works for simple people like myself.

My momma always says to use the KISS method....Keep It Simple Stupid