(Only for experienced teachers of chemistry!
Sulfuric acid is very corrosive. Work on a tray.
In the  previous experiment a lead cell was assembled to supply a LED with electricity.
Right photo (A - E): In a car battery six of such cells are connected in series.
1. Left photo: Make a model car battery by connecting six 5-ml vials with sticky tape,
2. adding 2 shiny lead sheets 1 x 6 cm and sulfuric acid 25% to each vial.
3. Place  6 plastic sheets between the electrodes for insulation.
4. Connect one electrode of each vial with the next one in the neighbouring vial.
5. Combine the + terminal of one 9- Volt battery with the - terminal of a  second one.
6. Connect the free electrodes in vials 1 and 6 to this 18-Volt battery.
Observations:      1. Gas bubbles at all electrodes.
                            2. The positive electrodes are covered by a brown layer.
Explanations:
1. Hydrogen gas is formed at the negative lead electrodes: 4 e^- + 4 H⁺(aq) --reduction--> 2 H₂(g),
2. Lead of the anodes reacts leaving lead dioxide                       2 H₂O+Pb--oxidation--> PbO₂+4 H⁺(aq)+4e^-