Circuitmess Wacky Robot Bob Instructions Manual page 24

Grab the photoresistor and gently
place it on the top of Bob's head.
Next, get two LEDs ready and position them inside Bob's eyes.
Here's where polarity matters, so pay close attention.
If you flip Bob around, you'll spot tiny + and - signs next to
each connector. Those symbols indicate the polarity.
On the LEDs themselves, look for the cut-off (-) and rounded
(+) parts – those mark the plus and minus sides. Match them
up with the right connectors, and Bob's eyes will light up.
Don't worry about which
way it's facing; either
way works just fine.