"Screaming jelly babies" is a chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 demonstration which is practised in school

School

A school is an institution designed for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is commonly compulsory. In these systems, students progress through a series of schools...

s in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, and other countries where the sweets are commonly available. It is often used at open evenings to demonstrate the more light-hearted side of secondary school science.
The experiment shows the amount of energy there is in a "jelly baby

Jelly baby

Jelly babies are a type of soft confectionery that look like little babies in a variety of colours. There are currently several brands of jelly babies, most predominantly Trebor Bassett , Rowntree , Norfolk Manor, and Haribo.Jelly babies were launched by Bassett's in 1918 in Sheffield...

". Potassium chlorate

Potassium chlorate

Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...

 is a very strong oxidizing agent that oxidizes the sugar

Sugar

Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 in the jelly baby almost instantaneously.

When the experiment is performed, the jelly baby bursts into flames and a screaming sound can be heard as rapidly expanding gases are emitted from the test tube in which the experiment is performed. The smell of candy floss is also given off.