It Must Be Monday

How can you tell if a wall is a bearing wall?
You need to look at what a wall is holding (or not holding) to know if it's a bearing wall.
Usually looking in the basement (if you have one) will allow you to see some, if not all, of the main floor floor joists. Usually these are resting on an outside wall and then meet somewhere in the middle. The American Rambler home is built as a long hallway with a wall down the center to hold the floor and ceiling joists.
Homes that aren't built this simply still, usually, have a center wall that holds up the floor joists.
Recently (well, actually in the past 20 years) has seen great development in using engineered floor systems (I joists, Engineered trusses). This allows for much greater spans without the need for a central bearing wall.

The second place to look for bearing conditions is to stick your head up into the attic. Most homes built before the use of roof trusses will usually have rafters (2x6 or 2x8 are the most common.) Also visible, perhaps underneath the insulation (wear a mask to avoid breathing in a pile of nasty dusts) should be the ceiling joists. These generally will meet on that same center wall (or on the second floor) still going in the same direction as the floor joists on the first floor.

In a remodeling project, one of the aspects of a home we try to understand is the "How was it built?" to decide how best to proceed with any project.