Science and Technology
Grade 5: Structures and Mechanisms: Forces Acting on Structures and Mechanisms
Overall Expectations
•demonstrate an understanding of the effect of forces acting on different structures and mechanisms;
•design and make load-bearing structures and different mechanisms, and investigate the forces acting on them;
•evaluate the design of systems that include structures and mechanisms, and identify modifications to improve their effectiveness.         
Specific Expectations
Understanding Basic Concepts        
•identify and measure forces acting on a structure (e.g., mass, air pressure), and describe the effects of their application;        
•identify the parts of a structure that are under tension and those that are under compression when subjected to a load (e.g., the wires in a suspension bridge are under tension; a ladder bearing a mass is under compression);        
•compare the force needed to lift a load manually with the force required to lift the load with a simple machine (e.g., lever, pulley system, gear system);        
•describe, using their observations, the advantages and disadvantages of using different types of mechanical systems (e.g., a single-pulley system has no mechanical advantage; a pulley system with two or more pulleys has a mechanical advantage);        
•describe the turning force (torque) of different combinations of gears (e.g., the turning force of a higher gear and of a lower gear);        
•identify the force required by different pulley systems (systems with one or more pulleys) to move a load, and compare the systems in qualitative terms.        
Developing Skills in Inquiry, Design, and Communication        
•formulate questions about and identify needs and problems related to structures and mechanisms in the outdoor environment, and explore possible answers and solutions (e.g., construct a bridge that must support a given load across a given distance; determine which surface of a cantilever bridge or beam is under tension and which is under compression);        
•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, in describing their investigations and observations (e.g., use terms such as component, subsystem, and device when describing 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., make a chart to record data on the raising of a load with different pulley systems);        
•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., give a presentation on the process of designing and making a specific structure);        
•design and make a frame structure that can support a load (e.g., a bridge);        
•make a mechanical system that performs a specific function (e.g., lifting a heavy load; retrieving an object from a position that cannot be reached by hand);        
•cut, join, and rearrange pliable and rigid materials to make an object (e.g., cut wood at a 45º angle to make a mitre joint; make a mould for a face mask);        
•describe safety measures to be taken to ensure their own safety and that of others (e.g., they need to check that fixed pulleys in pulley systems are secure before testing them).         
Relating Science and Technology to the World Outside the School        
•identify specific considerations in the actual manufacture of a product that they have designed and made (e.g., production time; cost and availability of materials);        
•identify problems that arose in the designing and making of a product, and indicate how these could have been avoided or how they were solved;        
•describe the consequences of having limited time and materials when making a product;        
•identify modifications intended to improve the performance, aesthetic appeal, and impact on the environment of a product they designed;        
•identify the aesthetic qualities of a product they made (e.g., form, colour, pattern, type of surface), and explain the usefulness of the product to others;        
•assess the effect of modifying a component of a system (e.g., a personal computer system that has a keyboard, floppy disk drive, CD-ROM, hard drive, central processing unit, and monitor);        
•assess the effect of modifying a subsystem that interacts with other subsystems within a system to perform a specific function (e.g., changing a pulley system to a lever system);        
•describe how different mechanisms (e.g., ratchet and pawl, cam and cam follower) are designed for a specific purpose or function;        
•recognize the advantages and disadvantages of using various mechanisms (e.g., levers, wheels and axles, pulleys, gears) with respect to the amount of energy they require to move or lift a given load;        
•describe the change in energy transfer that occurs when the number and the size of gears in a gear system are modified.         
Student Name:        
 Expectations: Copyright The Queen's Printer for Ontario, 1998.  Format: Copyright B.Phillips, 1998.