How to play Force Sort
Force Sort is a free KS3 physics game about balanced and unbalanced forces. Each question shows a short scene, like a book on a table or a ball falling through the air. You make two choices. First, decide if the forces on the object are balanced or unbalanced. Then pick the force that the scene asks about from a short list.
The words in the scene hold the clues. If the object starts, stops, speeds up, slows down or turns, the forces are unbalanced. If it stays still, or keeps going at a steady speed in a straight line, they are balanced.
A game has ten scenes. The first few are everyday ones. Later scenes are harder, such as a skydiver or a trampoline. Tick the harder start to skip the easy scenes. Each round has some balanced scenes and some unbalanced ones, so read each one with care.
You score 10 points when both of your choices are right. A 30-second timer runs on each scene. If it reaches zero, the scene scores nothing. The practice switch turns the timer off. On a keyboard, press 1 to 4 to choose and Enter to go on. The game keeps your best score on this device. The harder start has a best score of its own.
The science behind balanced and unbalanced forces
A force is a push or a pull. It comes from two objects acting on each other. In a diagram, you draw a force as an arrow that points the way the force acts. When forces act along one line, you can add them up. Two forces that point in opposite directions work against each other.
Forces are balanced when two opposite forces are the same size. They cancel out. KS3 science gives two examples. One is a weight held up by a stretched spring. The other is a weight resting on a squashed surface, like a book on a table. In both, the upward force matches the pull of gravity, so the object stays where it is.
Unbalanced forces change how an object moves. You need a force to make something start or stop moving. You also need one to change its speed or the way it is going. The change depends on the size of the force and the way it points. That is why a dropped ball speeds up and a sliding book comes to a stop.
Some forces only act when things touch. A spring pulls back when you stretch it and pushes back when you squash it. Friction acts when two surfaces rub together. Air resistance and water resistance act when an object has to push air or water out of its way.
Other forces act at a distance, with no touching at all. KS3 science names three of these non-contact forces. They are gravity, the force between magnets and the force from static electricity. Magnets can pull each other closer or push each other away.
This game covers the forces, balanced forces, and forces and motion parts of the KS3 National Curriculum for science. It uses words and scenes and leaves out numbers. For sums with forces in newtons, the GCSE game Resultant Force is the next step.
Tips for sorting balanced and unbalanced forces
- Look at the verbs. Speeds up, slows down, starts, stops and turns all mean the forces are unbalanced.
- Still or steady means balanced. A box pushed along at a steady speed has balanced forces, even though it is moving.
- The second question tells you what to look for. "Holds it up" points to a spring or a surface. "Slows it down" points to friction, air resistance or water resistance.
- Air resistance and water resistance are easy to mix up. Check what the object is moving through.
- Magnets can pull together or push apart. Either way, the force is magnetic.
A wrong answer or running out of time resets your streak. If the timer keeps beating you, switch on practice mode and take each scene slowly.
Use this in the classroom
Force Sort suits Years 7 to 9 when you teach forces and motion. A round of ten scenes takes about five minutes. That makes it a quick starter, or a check at the end of a lesson.
Show a scene on the board before anyone taps. Ask the class to sketch the force arrows for it, then ask if the arrows cancel out. The book on a table and the weight on a spring are good first examples, because the curriculum names them. The skydiver at a steady speed is a good one to argue about. Ask why its forces are balanced when it is clearly moving.
As a follow-up, ask each student to write one new scene for each force in the game. Then they swap and sort each other's scenes. The turning effect of a force is also part of KS3 forces, and Moments Balance lets students practise it.
The practice switch turns the timer off for anyone who needs more time. Nobody needs an account to play. Our page for teachers has more ideas for lessons.
Similar games
If the magnet scenes caught your eye, Electromagnet Workshop shows how an electric current can make a magnet. Pressure Dive looks at pressure in water. For KS3 chemistry, try Atom Detective. The physics games page lists the rest.
Questions people ask
Here are some questions that students and teachers ask about forces at KS3.
What is the difference between balanced and unbalanced forces?
Balanced forces are the same size and act in opposite directions, so they cancel out. The object stays still, or keeps moving at the same speed in the same direction. Unbalanced forces do not cancel out. They make the object start, stop, speed up, slow down or change direction.
Can a moving object have balanced forces?
Yes. Balanced forces mean the motion does not change. A box pushed at a steady speed has balanced forces, and so does a skydiver falling at a steady speed. The object would need an unbalanced force to speed up, slow down or turn.
What are contact and non-contact forces at KS3?
Contact forces act when objects touch. Friction, air resistance, water resistance and the push or pull of a spring are all contact forces. Non-contact forces act at a distance. KS3 science names gravity, the force between magnets and the force from static electricity.
Is Force Sort a good fit for Year 7?
Yes. The game uses everyday scenes and no numbers, and it follows the forces content in KS3 science. Year 7 students can start with the normal round. Students in Years 8 and 9 can tick the harder start for the trickier scenes.