Teaching Forces Background knowledge for teachers

NEWTONS LAWS OF MOTION 1. An object will stay at rest, or move at a constant speed, unless acted upon by an unbalanced force. 2. The acceleration of an object acted upon by an unbalanced force is directly proportional to the magnitude of the force and inversely proportional to its mass. 3. To every action force there is an equal and opposite reaction force. Newtons laws can confuse learners. The following slide provides simple explanations of Newtons Laws of Motion. At primary it is good for children to experience and discuss the effects of forces.

All Complicated Forces Explained 1. Balanced forces cause objects to stay at rest or travel at a constant speed. A bullet travelling through space just keeps on going. 2. Unbalanced Forces cause objects to speed up or slow down. Id rather push a Mini than a 4X4! 3. To every Action Force there is an equal and opposite Reaction Force. If you shove me Ill shove you back (at the same time)!

Elicit their ideas Get learners to discuss what they think prior to investigating Use interesting, engaging activities to get them thinking/wondering Find out any misconceptions All of the above are important before learners can new construct new meaning

Common Pupil Myth An object which does not move has no forces acting on it.

Balanced Forces Are there any forces acting on this cup?

Hang About! Try strings and arrows! Which forces are acting on This object? With a difficult concept such as upthrust from a table it can be useful to get learners to think about examples they can visualise e.g. a nail pushing up on a string, water pushing up on a boat.

Types of Forces Pushing Forces Pulling Forces Friction Different types of forces should be explored with learners. They need hands on opportunities to experience and investigate these and think about and discuss their ideas about everyday examples.

Buoyancy A few ideas for getting them talking, thinking and helping them to construct new meanings. Lava Lamp Dancing Raisins Water Density

Gravity Therefore, the Moon cant have Gravity because it doesnt have an atmosphere. Learners commonly have misconceptions about gravity e.g. The Earth has gravity because it has an atmosphere.

Challenging learners ideas about gravity Ask learners to draw forces diagrams which show where gravity is pulling when people are at different locations on Earth Use tennis balls that look the same but one is injected with water to explore Galileos theory Watch videos of astronauts on the moon and discuss how and why gravity is weaker on the moon

Fun with Gravity Galileo Astro-Blaster Centre of Gravity

Friction – possible activities O-Wings Gripping Rice! Potato Spears

Air Resistance – Possible Activities Streamlining Rockets

Great Resources Little Book of Experiments