What if you read the book aloud to someone, or a group of people?
What if you read it aloud to yourself, but others are within earshot?
What if you project it on a screen with an opaque projector? (Remember those days class?)
What if you're reading it to yourself, but someone is looking over your shoulder?
The answer is a definitive "it depends"
You can read a book to your kids... and maybe even to a few of your kids' friends who come over for a sleepover... but you can't have an event where you do a public reading and invite the neighborhood without risking the copyright police coming to knock.
You can sing "happy birthday" to your kids... but if Chili's employees sings it to you at the table then they would have to pay a royalty to the license owner.
A lot of it is about intent of use. Some people will try to push the limits and blur the line... but most people really know better, they just choose to ignore the limits.
In most cases, if you find yourself asking "is this ok" that is the first sign that it might not be ok, and that you already know that.