Warning: Bleach releases smelly fumes during this reaction.
You will need:
Sodium hypochlorite bleach
Manganese dioxide from charged battery
Add the bleach to the test tube. Add the manganese dioxide. After a few minutes, the solution should become light pink as the tinest trace of permanganate leaches out. After 24 hours, the solution should be brilliant magenta. If the battery was not charged, the manganese(III) is oxidized to manganese(IV), using up the bleach. If it is slightly discharged, the manganese(III) and the manganese(VII) will comproportionate, producing manganese(IV) again and the solution will become colorless after about 2 days. Here is the solution. It is very very dilute, but still brilliantly colored. If you are looking for a measurable yield from this reaction, do not complete it.