On the board some lamps are glowing - filled circles are on, empty ones are off.
You press a lamp: it toggles, and so do the four neighbors above, below, left and right.
Work out which lamps to press so that in the end all lamps are off.
Example
For parents
What does this exercise practice?
Lights out trains careful looking and thinking ahead - every lamp affects its neighbors, so the child always plans two steps ahead.
Common pitfalls
Pressing away at once quickly gets confusing. It helps to think about which lamp you would press last and work backwards through the board.
How to practice at home
Play it with paper squares - one sheet means the lamp is on, an empty spot means off. When you flip a sheet, the four neighbors flip too.