Words that start with R
25 words start with R. Show all words
R
- Radius Maths
- The distance from the centre of a circle to its edge. It is half the diameter.
- RAM Computers
- A type of computer memory that holds the things you are working on right now. It empties when the power goes off.
- Ratio Maths
- A way of comparing two amounts. If there are 2 boys for every 3 girls, the ratio is 2 to 3.
- Reciprocal Maths
- The number you get by flipping a fraction upside down. The reciprocal of 2/3 is 3/2.
- Rectangle Maths
- A four-sided shape with four right angles, where opposite sides are the same length.
- Recycle Science
- To turn used things like paper or glass into new things instead of throwing them away.
- Reflection Science
- When light or sound bounces off a surface, like your face in a mirror.
- Reflex angle Maths
- An angle bigger than a straight line but smaller than a full turn, between 180 and 360 degrees.
- Refraction Science
- The bending of light as it passes from one material into another, like a straw looking bent in water.
- Remainder Maths
- What is left over when a number cannot be divided exactly. 13 divided by 4 is 3 with a remainder of 1.
- Renewable energy Science
- Energy from sources that do not run out, like sunlight, wind and flowing water.
- Reptile Science
- A cold-blooded animal with dry scaly skin, like a snake or a lizard.
- Resistance Science
- How much a material pushes back against an electric current.
- Respiration Science
- How living things use oxygen to release energy from food.
- Rhombus Maths
- A four-sided shape with all four sides the same length, like a diamond.
- Rhyme English
- When words end with the same sound, like "cat" and "hat".
- Rhythm English
- The beat of the words in a poem or song.
- Riddle English
- A puzzle in words that asks you to guess the answer.
- Right angle Maths
- An angle of exactly 90 degrees, like the corner of a page.
- Robot Computers
- A machine that can sense things and be programmed to do tasks.
- Rock Science
- A hard natural material that makes up the Earth's crust.
- Root word English
- The basic word that other words are built from. "Play" is the root of "playful" and "replay".
- Rotation Science
- Turning around a centre. The Earth rotates once about every 24 hours, giving us day and night.
- Rounding Maths
- Changing a number to a nearby one that is easier to use, like 47 to 50.
- Router Computers
- A device that sends internet signals to the computers and phones in your home.