Resources: Strong cardboard, lolly sticks, paper straws, sellotape, thin dowel/cocktail sticks, plasticine, sticky tape, glue, a compass and scissors.
Core Handout (2): A planning sheet so children are able to design their gear system and then ask prompt questions to show their understanding of how gears work.
Stretch Handout (3): Examples of gear mechanisms that ask children to predict how many times the smaller gear will turn.
Enquiry Approach - Problem-solving
Applying prior scientific knowledge to solve problems and answer further questions.
Enquiry Skill - Observing and measuring
Using the senses and taking measurements, using a range of equipment, to make observations about a scientific enquiry.
Ask the children to discuss why pulleys and levers are useful and give some examples of where they would expect to find pulleys and levers. Encourage them to recall their results from the previous lesson; that levers and pulleys allow a smaller force to have a greater effect.
The children will learn about a further mechanism - gears. Gears are toothed wheels that mesh together and interact with each other. When 2 gears grind together, they will rotate in opposite directions.
Gears are designed to do 3 things:
1. Change the direction of motion;
2. Change the speed of motion;
3. Change the amount of force.
Explain the relationship between the number of teeth gears have and how fast or slow they rotate. For example, if one gear has 32 teeth and is connected to a gear that has 8 teeth, the smaller gear will have rotated 4 times in the time it takes for the larger gear to turn once.
Explore the workings of different types of gear, such as worm and wheel gears and bevel gears.
Career Film: Take a tour around Rolls Royce SMR's Heritage Museum in Derby to find out about Elliott Thompson's job. Elliott works as the Reactor Island Verification Lead for Rolls Royce SMR.
Expert Film: This is Matthew McCormack. Matthew works as the Manufacturing Engineering Manager for Rolls Royce SMR. Listen to Matthew as he describes gears.
Ask the children to design and create a set of 3 gears that interact with each other. Label each gear A, B & C and state how many teeth it will have. Predict which way each will rotate (e.g. when A is turned clockwise, B will turn anti-clockwise) and how many times. The children will then turn their gears to test whether their predictions were right. The children who require support should create gears with lolly sticks, so they are able to easily count the teeth. They can be challenged to make more complicated gears by cutting teeth into the cardboard.
Challenge Task: What patterns can they observe between the number of teeth on a gear and how many times another gear will turn? Can they predict how many times the gears will turn in the examples provided?
In small groups, ask the children to show their gears interacting and explain how they work. Encourage them to say which way each gear will rotate and how many times (based on the number of teeth the smaller/larger gear has).
Gears are a type of mechanical component that transmit motion and power between two rotating shafts. They consist of toothed wheels that mesh together to transfer rotation from one shaft to another.
Gears are classified according to their shape, size, and application. Some of the common types of gears include:
Spur Gears: These are the most common type of gear and are used to transmit power between parallel shafts. They have straight teeth that run perpendicular to the gear's face.
Helical Gears: These gears are similar to spur gears but have angled teeth. They are used to transmit power between parallel shafts and are quieter and smoother than spur gears.
Bevel Gears: These gears have teeth that are cut on a conical surface and are used to transmit power between intersecting shafts.
Worm Gears: These gears are used to transmit motion between shafts that are perpendicular to each other. They consist of a worm (a screw-like shaft) that meshes with a worm gear.
Gears work by transferring power between two rotating shafts. As one gear rotates, it meshes with the teeth of another gear, causing it to rotate in the opposite direction. The speed and direction of the second gear can be controlled by changing the size and shape of the gears.
Gears are widely used in many applications, including automobiles, bicycles, machinery, and even clocks. They are popular due to their ability to efficiently transfer power between shafts, even when they are not located in close proximity to each other.
In conclusion, gears are a fundamental component of many mechanical systems, providing an efficient way to transfer power between rotating shafts. They come in different shapes and sizes, each with its own specific application. Gears are essential for a wide variety of mechanical systems, from simple clock mechanisms to complex industrial machinery.