Salt Water Battery – Rough Lesson Plan

• Reminder of electricity concepts: current, circuits. Make sure they get the idea of a complete circuit, and that the battery provides the energy in the circuit. Energy comes from chemical reactions in the batter, turns to electrical energy, turned to light by lightbulb.

• Show pre-made demo of salt-water experiment (now, you can make your own!). Show how simple the materials are.

• So how can this be used as a battery? It produces an electrical current. What is current made of? Talk about current as a stream of charges. Battery “pushes” them around. Go over how charges behave.

DEMO: Show magnets attracting/repelling each other to show how opposite/same charges behave.

• Explain the anode and cathode reactions (cathode – charchoal – eats electrons) (anode- aluminum – produces electrons). Draw a diagram of the salt water battery on the board. Show how charges are forced to move through wire as current.

• But why is there salt? Explain electrodes: if electrons want to go to the cathode, eventually it will negative! But, luckily there is salt inside the battery!

• Explain electrolyte: Salt is awesome. Salt is made of two ions together. Anions and cations move to cancel out excess charge → continued current!

EXPERIMENT: Hand students out materials for salt water batteries, let them make them in pairs.

FRONT OF CLASS DEMO: Invite pairs up to front of class to connect their batteries until an LED lights.

• Explain why connecting the batteries lets them let the LED light: Series connection! Voltage adds up.

ACTIVITY: Have a “who can light up the most LEDs” the fastest competition in groups of pairs. If possible, connect all the series of batteries together in parallel to power small device (e.g. clock/radio).

• (If this works!) explain about parallel connection – how current is added together.

Q&A time

• If enough time/part of a larger lesson, design challenge could be done on how to build better batteries – taking into account surface area, cell arrangement etc.