Sequence planning: Assess prior knowledge!
– air is all around us
– wind is moving air
– air fills up spaces if allowed
– air can push or cause pressure on things
– air slows down falling objects such as paper, balls and parachutes
– the shape and size of an object affects the nature of airflow around it, hence the air resistance
– planes and other flying things are held up by the force of air on their wings
What is air?
– Nitrogen – 78%
– Oxygen ~ 21%
– Carbon dioxide ~ 0.04%
– Argon ~ 1%
Middle primary need to know the concentration for each component.
Idea that air/gas moves is extremely important.
Concept of pressure
– real life situations – pumping up a tyre
– force applied to a given area
Wind resistance is important for knowing why people use parachutes etc
Idea that shape and size importance for concept of aerodynamics.
Try not to make leaps in learning, the sequence you teach science is important.
Change in language.
– air in the atmosphere exerts a pressure in all directions
– the atmosphere can exert a surprisingly strong force on objects
– ‘sucking’ reduces pressure, causing a force imbalance towards the low-pressure region (consider what the know about ‘force’ then ‘force imbalances’, easiest would be the concept of push and pull or Newton’s first law)
– the pressure of air is used in many applications (tyres, hoists, etc)
– air pressure differences tend to equalise
– a moving stream of air has reduced pressure
– air has weight (part of the problem is how we define weight)
– air expands on heating, causing a pressure increase if it is contained
– hot air is less dense (or more spread out) than cold air, and rises
– air consists of a mixture of gases, one of which (O2, dioxide) is necessary for burning
– objects can be shaped to either minimise or maximise the force of air on them
– a flat object such as a plane wing, a boomerang or a paper tube can be supported by forces that arise due to differences in airflow across the top and bottom surfaces
– to every action there is an equal or opposite reaction: a stream of air (or water) forced from a balloon or rocket will cause a force back on the balloon or rocket to propel it
– the force from air on a moving object depends on the surface area, and the shape of the object
– wind is moving air