Visual thinking is most often associated with commercial, fine, or industrial arts. But visual thinking plays a big role in science, too. Before cameras and computers, scientists would draw whatever they were studying because, in the words of Ralph Waldo Emerson, "Many go through the meadow, but few see the flowers in it."
Drawing forces you to really look at whatever you're drawing. The more closely you look, the more likely you are to see things you or others may have missed. To become a better visual thinker, draw something!
The whisk above is another page from my high school sketchbook.