reflex

Everyday

1. A reflex is something your body does by itself, very quickly, without you deciding to, such as blinking when something flies at your eye or pulling your hand off a hot pan. tree →
2. Reflexes are how quickly you can react: a goalkeeper with fast reflexes. tree →
3. In maths, a reflex angle is an angle bigger than 180 degrees but smaller than 360 degrees. tree →

In the lessons

In science (the body), reflexes protect you: the message goes from the nerves to the spinal cord and straight back to the muscles, faster than thinking; the doctor taps your knee to test the knee-jerk reflex. In maths, angles are named acute (less than 90°), right (90°), obtuse (between 90° and 180°), straight (180°) and reflex (between 180° and 360°). In sports and stories it shows quick reactions. Phrases: quick reflexes, a reflex action, reflex angle.

Examples

• I blinked as a reflex when the ball flew at my face. tree →
• Pulling your hand away from a hot plate is a reflex. tree →
• The doctor tapped my knee and my leg kicked by itself. tree →
• Our goalkeeper has amazing reflexes. tree →
• A reflex angle is bigger than a straight line. tree →
• An angle of 270 degrees is a reflex angle. tree →
• Sneezing and coughing are reflexes that clear your nose and throat. tree →

Note

Plural: reflexes. A reflex is not chosen, so you cannot easily stop it. Maths trap: a reflex angle is more than 180° but less than 360°; 180° exactly is a straight angle, 360° a full turn. To find a reflex angle from the small angle on the other side, subtract from 360: if the small angle is 60°, the reflex angle is 300°.