Featured Image No Longer Cropping

I just noticed this morning that my featured images are no longer being cropped to fit nicely into the featured image thumbnail displays on my home page. I have always made my featured images fairly wide to accommodate the proportions preferred by Facebook, as that is where most of my traffic comes from. Until recently, these wide featured images were always cropped on my home page so that the image thumbnails that showed with each post preview were OK-looking; not ideal, but at least the frame was always full.

This morning, many of them look terrible. WP is now taking the whole wide image in its entirety and cramming it into the frame, which often results in a white bar of nothing across the bottom (sort of a white equivalent of what you’d get with a letterbox view of a widescreen movie on an older TV set).

If you look at my home page and just start scrolling, you’ll see that about half of these are like this: http://www.cultofpedagogy.com

It looks like crap. How do I fix this? Thanks.

P.S. I do not know any kind of advanced code. I can go into CSS and kind of replicate things I’ve tried in “Inspect Element,” but that’s about it.