* A lens or magnifying glass, bigger the better * A newspaper sheet with lot of writing * Sunny day * A tray that will not burn easily
Go out on a sunny day and place the newspaper crumpled as a ball on the tray. Take the lens or magnifying glass and focus the sun over the newspaper ball. Adjust it by moving it up and down till you have a small focussed point on the newspaper ball. Be careful to not touch the newspaper as it will be hot and may even form a hole. Observe what happens and conclude.
The magnifying glass focuses all the light from the sun on a tiny spot on the newspaper making it to turn hot and burn. This is also the energy saving principle of solar cookers.
A magnifying glass or lens helps focussing all the light from one side to the other side and the newspaper starts burning until the whole newspaper ball is burnt.