Science and Technology
Grade 4: Structures and Mechanisms: Pulleys and Gears
Overall Expectations
•demonstrate an understanding of the characteristics of pulleys and gears;
•design and make pulley systems and gear systems, and investigate how motion is transferred from one system to another;
•identify ways in which different systems function, and identify appropriate criteria to be considered when designing and making such systems.         
Specific Expectations
Understanding Basic Concepts        
•describe, using their observations, the functions of pulley systems and gear systems (e.g., they make changes in direction, speed, and force possible);        
•describe, using their observations, how rotary motion in one system (e.g., a system of pulleys of different sizes) is transferred to rotary motion in another (e.g., a system of various gears) in the same structure;        
•describe, using their observations, how gears operate in one plane (e.g., spur gears, idle gears) and in two planes (e.g., crown, bevel, or worm gears);        
•demonstrate an awareness of the concept of mechanical advantage by using a variety of pulleys and gears.         
Developing Skills of Inquiry, Design, and Communication        
•formulate questions about and identify needs and problems related to structures and mechanisms in their environment, and explore possible answers and solutions (e.g., test the effort required by different gear systems to lift the same load);        
•plan investigations for some of these answers and solutions, identifying variables that need to be held constant to ensure a fair test and identifying criteria for assessing solutions;        
•use appropriate vocabulary, including correct science and technology terminology, to describe their investigations (e.g., use terms such as block and tackle in describing pulley systems and gear train in describing gear systems);        
•compile data gathered through investigation in order to record and present results, using tally charts, tables, and labelled graphs produced by hand or with a computer (e.g., create a table recording how the action of a pulley system is altered by changing the tension of the band connecting two pulleys);        
•communicate the procedures and results of investigations for specific purposes and to specific audiences, using media works, written notes and descriptions, drawings, charts, and oral presentations (e.g., draw a diagram of a proposed object and a diagram of the finished product);        
•design, make, and use a pulley system that performs a specific task (e.g., a pulley system that closes a door or carries an object from one place to another);        
•design and make a system of pulleys and/or gears for a structure (e.g., a potter’s wheel) that moves in a prescribed and controlled way (e.g., fast, straight) and performs a specific function;        
•manipulate pliable and rigid materials (e.g., modelling clay, wood) as required by a specific design task.         
Relating Science and Technology to the World Outside the School        
•demonstrate awareness that most mechanical systems are fixed and dependent on structures (e.g., elevators);        
•compare in qualitative terms the performance of various mechanical systems (e.g., a block-and-tackle system, a single-pulley system), and describe how they are used;        
•identify and make modifications to their own pulley and gear systems to improve the way they move a load (e.g., change the size of pulleys or gears used; use gears that change direction through a right angle);        
•evaluate, in general terms (e.g., as more or less effective), the performance of a system that they have made and the performance of another system designed to do the same task;        
•explain how various mechanisms on a bicycle function (e.g., levers for braking; gears and chains for changing speed);        
•demonstrate awareness that finishing techniques can adversely affect the performance of a mechanical system (e.g., problems result if paint gets into a gear system);        
•identify the properties of materials (e.g., pliability, rigidity) that are best suited for use in a structure that contains a mechanical system;        
•describe the consequences of having a limited choice of materials when making a device or a structure;        
•identify common devices and systems that incorporate pulleys (e.g., clotheslines, flagpoles, cranes) and/or gears (e.g., bicycles, hand drills, wind-up or grandfather clocks).         
Student Name:        
 Expectations: Copyright The Queen's Printer for Ontario, 1998.  Format: Copyright B.Phillips, 1998.