It is very easy to confuse texture with pattern, especially if the object reference has a relatively uniform pattern on the surface. i made this mistake on a first attempt as practising the exercise. I chose a woven pot holder that seemed like a good idea because the surface is very contoured with a lot of obvious shadow, but those contours are very uniform and regular. the 'trap' in using this type of surface is that the brain keys on thr pattern and not the shadows that define the contours. Observing drop shadow finally clicked in my brain when I chose a surface that was as randomly rough as possible with no discernable pattern that could be drawn without direct observation of the object... that is the mental trap for me - if the texture is uniform and repeatable, my brain reverts from drawing what I see to drawing the pattern from memory. Brains love patterns.

The fried chicken surface texture in the lesson is a great example of random texture, but it is a complex object. I needed something much more simple. Crumpled paper works, but there are some ways to make it easier to observe the drop shadows, which might help just to give your eyes and brain a very clear example to start with. First, don't crumple the paper... randomly fold it as many times and in many directions as possible. Think origami. Them open the sheet up and press it flat. Shine a light on the paper from a side angle that is elevated, but not more than 45degrees, which will create distinct shadows. Then take a photo of the surface from directly over the page, not for use as a reference to draw from, but as a way to give your brain an example of what your drawing on a flat piece of paper will look like. It helps to edit the photo by boosting the contrast a lot. Then spend some time mentally comparing the photo to the paper and linking the shadows on the paper to the shadows in the photo. I know this sounds like a lot, but it is really about five minutes of effort. The objective, for me at least, was to try to make it as easy as possible for my brain to register the drop shadows observed in a texture by eliminating as much distracting stuff in the observation as possible.

I did this only as an exercise to think about and did not save that high contrast photo, or even draw that example, so I cannot post it. i will recreate it and try to post and example, but we are literally packed up and starting a move today.