University professor here: showing and decoding wire signals has become a staple in my teaching - very effective, eye-opening even for students that find the OSI layers too abstract to grasp on paper. Btw, I’m using this nice demo board (I’m not affiliated with the brand): https://www.batronix.com/shop/demoboards/Batronix-MSO-Demo-B...

…typically we decode I2C.

Oh, I‘ve equipped the lab with all kinds of oscilloscopes. I find a lower mid-tier product (like Rigol DHO 900/1000 series) most suitable: good enough resolution and nice quality-of-life features (many physical buttons / dials and input channels go a long way!), yet not too feature-packed and physically compact to still be approachable.