Students focus on the mathematical skills and mental calculations (recall of multiplication and division facts, recognition of common factors and multiples) associated with using ratios in a problem-solving context.
Learning object description:
Examine a pair of gears that drives a conveyor belt to an oven. Notice that the number of rotations for each gear depends on the gear size (number of teeth). Explore the relationship between the number of teeth and the number of rotations. Build a graph to compare rotations for a range of gear sizes. Look for a number pattern. Choose a gear to adjust the speed of a conveyor belt. For example, choose a gear size (15 teeth) that will turn five times for every turn of the driver wheel (75 teeth). This learning object is the second in a series of six objects that progressively increase in difficulty.
Key learning objectives:
Students use knowledge of factors and multiples to solve problems.
Students apply ratios to solve multiplicative problems.
Educational value:
Demonstrates that factors, multiples and common multiples are integral to solving problems involving ratios.
Provides opportunities for students to practise multiplication and division operations in ratio situations.
Encourages students to use multiplicative strategies and ratios to interpret and describe relationships between objects.
Provides data tables for students to record observations and predictions.
Automatically collates data tables and displays number patterns on line graphs.
Learning area:
Mathematics
Keywords:
Diameter; Factors; Gear ratios; Line graphs; Linear equations; Multiplication; Multiplicative thinking; Number patterns; Ratios; Rotation; Tables (Data)
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