Question

how do you make electrons jump? use a battery! there are two different kinds of metal in a battery. a special liquid is put between them. the liquid breaks down some of the metal. this lets go of electrons. because the metals are different, one metal lets go of electrons more easily than the other metal. the other metal takes the electrons. so, the electrons start to move from one metal to the next through the liquid. this creates a current. and that is how batteries make electricity! need help? if your led light bulb does not light up, switch the bottom and top wires. the light bulb will only work if its wires are in the right place. also, make sure the cardboard squares are not touching one another. to make the electrons jump, the two different kinds of metal must be connected by the liquid in the cardboard. if the cardboard pieces touch, the electrons will go from one cardboard piece to the other and skip the coins. what should be checked if the experiment does not work? the wires and the squares the liquid and the foil the electrons and the battery the coins and the bulb

Explanation:

The text says to check wire placement (switch wires if LED doesn't light) and ensure cardboard squares (with liquid/metal) don't touch. So when an experiment fails, checking the wires (for correct placement) and the squares (to ensure they aren't touching, maintaining the electron - flow path through coins/liquid) is logical. Other options: "the liquid and the foil" has no foil - related check info; "the electrons and the battery" is too vague; "the coins and the bulb" – the text focuses on wires/squares, not coins - bulb directly.

Answer:

the wires and the squares