Science and Technology
Grade 7: Structures and Mechanisms: Structural Strength and Stability
Overall Expectations
•demonstrate an understanding of the relationship between the effectiveness of structural forms and the forces that act on and within them;
•design and make a variety of structures, and investigate the relationship between the design and function of these structures and the forces that act on them;
•demonstrate an understanding of the factors (e.g., availability of resources) that must be considered in the designing and making of products that meet a specific need.         
Specific Expectations
Understanding Basic Concepts        
•classify structures as solid (or mass) structures (e.g., dams), frame structures (e.g., goal posts), or shell structures (e.g., airplane wings);        
•demonstrate awareness that the position of the centre of gravity of a structure (e.g., bridge, building, tower) determines whether the structure is stable or unstable;        
•describe, using their observations, ways in which different forces can affect the stability of a structure (e.g., certain forces may cause a structure to shear, twist, or buckle);        
•demonstrate awareness that the effect of forces acting on a structure under load depends on the magnitude, direction, and point and plane of application of the forces;        
•identify forces within a structure that are affected by forces outside the structure (e.g., shear, torsion, tension, and compression within a bridge are affected by external forces such as high wind or ice);        
•measure the performance of a structure (e.g., a bridge, a tower) by comparing its mass with the mass of the load it supports.         
Developing Skills of Inquiry, Design, and Communication        
•use appropriate techniques and materials (e.g., cutting and joining pieces of wood or plastic) while making structures that have mechanisms;        
•formulate questions about and identify needs and problems related to the strength of structures, and explore possible answers and solutions (e.g., determine what caused structural failure and propose ways of supporting a specific 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 communicate ideas, procedures, and results (e.g., use terms such as fields, data, and cells when describing databases);        
•compile qualitative and quantitative data gathered through investigation in order to record and present results, using diagrams, flow charts, frequency tables, bar graphs, line graphs, and stem-and-leaf plots produced by hand or with a computer (e.g., tabulate data from tests of the strength of their own structures; record their evaluations of possible solutions to a design problem);        
•communicate the procedures and results of investigations for specific purposes and to specific audiences, using media works, written notes and descriptions, charts, drawings, and oral presentations (e.g., create an animated film of the steps taken in designing and making a product).         
Relating Science and Technology to the World Outside the School        
•tell the “story” of a product used every day, identifying the need it meets and describing its production, use, and eventual disposal;        
•investigate ways in which research is done on existing products (e.g., basketball shoes, telephones) to generate new ideas for the products;        
•recognize the importance of researching needs and opportunities for sale before proposing ways of developing a product;        
•recognize that a solution to a problem may result in creating new problems in other areas, and that a solution to a problem may be found while one is working on solving a problem in another area;        
•identify energy as a significant cost in the manufacturing and use of products or systems;        
•produce a work plan that outlines the possible criteria for choosing resources for manufacturing a product that they have designed (e.g., the properties and availability of the resources; the aesthetic appeal of the product and the impact of its use on the environment);        
•describe, using their observations, the function of symmetrical design in structural and mechanical systems (e.g., in bridges);        
•use their knowledge of materials in designing and making structures that will stand up to stress;        
•demonstrate how information is organized and stored in a computer system (e.g., in a database or a spreadsheet program).         
Student Name:        
 Expectations: Copyright The Queen's Printer for Ontario, 1998.  Format: Copyright B.Phillips, 1998.