How does electroscope work ?

Use the white paper strips and fold the strips into half so that you make a mark of fold. Open the strip and iron it lightly as shown in figure.

Hold the strip by pinching it at the fold. You would notice that the two halves move apart. This shows that the strip has acquired charge on ironing.

When you fold it into half, both the halves have the same charge. Hence they repel each other.