I would choose one of these in a heartbeat

I would choose one of these in a heartbeat - the stethoscope - measuring the students heartbeat. and mine proving that I was alive and not was some of the students thought part of the living dead. Also used the electronic one so the students could hear what they were supposed to hear.
 

Ores

 Looking at some ores. This is Peacock ore from Peru. The proper name is Bornite. It is a metal sulfide with the chemical composition Cu5FeS4. One of my prettiest ores.

Iron filings in 3D

Seeing old things n a new way is often what sparks off the imagination and the want and desire to find out new things in science. Using this 3D view of iron filings does just this. Leave it out in the lab for the students to find.

Organic Synthesis

 Starting the organic synthesis pathway diagram I was taught this by my Chemistry teacher some 40 years ago and it is still as relevant today.

Optics

 I find it a shame that some things creep out of syllabi. Less and less is done on optics and the students have little idea of the nature of lenses and images. In the Edexcel syllabus we spend time understanding why the candle was upside down on the screen.

Like and unlike charges

 Like charges repel and unlike charges attract

Looking at the converging lens

 These flat lenses work well with the @pasco light with its 5 ray beams. Working in a Light box the students can work in bright daylight and get excellent results.