IchigoJam has 7 output pins (using OUT1-6 & LED, maximum 11 pins when IN1-4 change to output).
This is the easiest demo using 7 LED parts without soldering.
It's very easy to connect the LED with female/male jumper wires.
Before warkshop prepare a pin socket connected all pins to extend GND.
Tape for safe.
I found the best way to connect the Photo Transistor with a mini jumper and resistor (10kΩ).
There goods are for KIDS IoT Hackathon!