A frog's life cycle

It has rained on and off for a week. Avadhi and Aayush, in full-sleeved shirts and full pants, walk with their class and science teacher to a shallow pond surrounded by trees and tall grass. The teacher asks them to watch from a distance and disturb nothing. Near the edge, on the water or stuck to plants, there may be a white jelly-like mass: a cluster of frog's eggs, called spawn.

A frog's life cycle has four stages, in this order:

• Stage I, egg: the spawn (day 1), which develops into the embryo (day 3–4).
• Stage II, tadpole: first a tadpole with a tail and no legs (day 7–10), later a tadpole with legs (8–10 weeks).
• Stage III, froglet (12 weeks).
• Stage IV, adult frog (14 weeks).

Each stage has what it needs. Tadpoles grow legs but keep their tails, which help them swim. As they grow they start to look like little frogs, called froglets. Froglets still live in water but begin to spend some time on land.

The froglets keep growing and lose their tails completely. Their legs grow strong for jumping and landing. At last they become adult frogs, which live both in water and on land.