Quote
1. Quote - Listen to the quote and guess what the slang means.

“The way that I have always made music, my rule of thumb, is just to make what I love.”
Singer Amy Lee (Evanescence), talking about how she likes to make music (BrainyQuote)
Definition
1. Definition - Study the definition.
good idea to use; rough guideline
2. Use - Learn how the slang is used.
If you find yourself in the middle of nowhere, one of the first things you will need to do is get water. You cannot survive very long without water, but it’s important to make sure the water you drink won’t make you sick. It’s a good rule of thumb to only drink from water that is moving, like from a river or stream.
A rule of thumb is an easily understood general way of doing something. A rule of thumb may not be completely reliable, but they are easy to use if you have no better option. The expression comes from the fact that the distance from the end of your thumb to the first bend is about an inch. It won’t be completely accurate if you measure things with your thumb, but it’s often good enough.
Singer Amy Lee says that her rule of thumb is to only make music that she enjoys making. She might be able to make more money or get more fans if she changed her style, but she just likes making music the way she wants to.
What rule of thumb do you use most often?
Examples
1. Examples - Hear some example sentences.
“As a rule of thumb, I always bring an umbrella when it’s cloudy. You never know, it might rain.”
“It’s a good rule of thumb never to trust anyone with your passwords.”
“It’s good to arrive late to parties and early to job interviews. That’s my rule of thumb.”