Each group needs:

• laptop or desktop computer with USB cable and Internet access
• 2 x 20 cm lengths of 22 gauge single-strand insulated copper wire; available at hardware stores
• 2 x 10 cm lengths of 32 gauge nichrome wire; such as from Amazon
• wire stripper
• plastic barrel from a disposable pen, such as a BIC pen
• electrical tape
• four plastic cups, for the four test solutions
• half-size or larger breadboard, such as the reasonably priced boards at Amazon
• assorted jumper wires, such as a pack of 30 7-inch wires (PRT-11026) at Sparkfun
• 470 Ω resistor, such as the resistor multipacks at Amazon
• red LED, such as the basic red 5 mm LED (COM-09590) at Sparkfun
• 9V battery
• 2 x 9V battery connector, such as the heavy-duty 9V snap connectors at Amazon
• Arduino UNO, such as the Rev3 or equivalent 
• 16 x 2 LCD display, such as the basic 16-character by 2-line display with black text on green background (LCD-00255 ROHS) at Sparkfun, or equivalent
• 10K Ω trimpot (aka trimming potentiometer, a small variable resistor), such as the trimpot 10K with knob (COM-09806) at Sparkfun
• 10K Ω resistor, such as the resistor multipacks at Amazon
• 220 Ω resistor, such as the resistor multipacks at Amazon
• Build and Test a Conductivity Probe Lab Handout, one per person

To share with the entire class:

• soldering iron(s), such as at Amazon
• lead-free solder, a few tubes to share among one class, such as at Amazon
• table salt, 250 g
• sugar, 250 g
• spoons or spatulas
• wax pencil or tape and marker, to label the cups
• distilled water, expect 1 gallon to be enough for an entire class
• tap water and sink drain
• paper towels, for drying the rinsed probes
• additional supplies may be needed to enable students to use their conductivity probes to conduct end-of-activity experiments of their own designs, for example, solutions of common household chemicals, lemon juice, sodium hydroxide, ammonia, at varying concentrations and temperatures