I love using visual aids to educate myself. I wish that I had more of them available when I was growing up. Heck, I wish that I could use them more extensively in my current self-education.
That's why I like this little animated clip. It depicts a biological assay that's used to capture the secretory footprints of blood cells. Certain B cells will secrete certain antibodies, for example. Additionally, different T cells will secrete different types of cytokines. That's the kind of assay that's depicted here. It shows how many T cells responded with a given cytokine to a particular type of stimulus.