Need qualified kicks in writing BEM classes?

Question

css

Hello. In general, I'm trying to figure out how to do it right. I reviewed a bunch of video lessons, read on the site and still can’t enter exactly. It turned out awful. In general, I'm at an impasse. I got to the point that I could not attach hover to the picture.
Here is the code: codepen.io/TurboWeb/pen/WRoObP?editors=1100 At the very end there will be a code like it looks like for me in SASS

Answer 1

I've already found one mistake.

<div class="small">
  <div class="item item--one">
    <div class="item__hidden item__hidden--one">

but it should be

<div class="small">
  <div class="small__item small__item--one">
    <div class="hidden hidden--one">

well I think so. especially the question about the hidden block

Answer 2

try instead

<div class="block block_mod">
  <div class="block__elem block__elem_mod">

So

<div class="block block_mod">
  <div class="elem elem_mod block__elem">