Primary General Science Glossary

This is a general primary science glossary. For class specific glossaries please go to the specific subjects

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A tubular instrument containing loose bits of coloured glass, plastic, etc. reflected by mirrors so that various symmetrical patterns appear when the tube is held to the eye and is rotated


A toy wind instrument that has a membrane that makes a sound when you hum into the mouthpiece.


Kelvin is the fundamental unit of temperature adopted under the Systeme International d’Unites (SI).  It is not calibrated in terms of the freezing and boiling points of water, but in terms of energy itself.  The number 0 K is assigned to the lowest possible temperature, called ‘absolute zero’.

Kilowatt hour

A kilowatt-hour (kWh) is a standard metric unit of measurement for electricity consumption for billing purposes. It can simply be described as 1000 watts of electricity used for one hour.

Kinetic energy

The energy possessed by an object by virtue of its motion is called kinetic energy.  The greater the mass or speed of the object, the greater is the kinetic energy.  Kinetic means active or moving.  Kinetic energy can be defined as energy in motion or the energy of a moving object.

Knee-jerk reaction

The involuntary contraction of the leg when the knee is tapped with a doctor’s mallet.