Lesson Plan : Machines that turn

 Teacher Name: R. Kingsley Grade: Grade 7-8 Subject: Science

 Topic: Wheels that turn Content: We will be studying machines that turn, from basic wheel and axle to winches,gears, gear trains and chain and sprockets. We will be looking at ways of calculating the mechanical advantage of these and the velocity ratio of gears in particular. Goals: To help students understand simple machines that use circular motion to perform work. To help students see a link between wheel and axle machines and levers. To promote the understanding of the direction of movement in systems such as gears, gear trains and chain and sprockets. To help students calculate the mechanical advantage of wheel and axle instruments. Objectives: Students will be able to design models of simple wheel and axle structures such as steering wheels, gears and gear trains. Students will be able to calculate the mechanical advantage of winches and wheel and axle instruments. After further investigation, students will be able to draw low and high gears for a bicycle and explain how they are used to perform different tasks. Materials: Models of machines that turn and the basic structures that make them work: manual mixer,corkscrew,rudder on a boat, simple winch (LEGO)... Introduction: We will first list simple machines that could fit into the category of machines that turn. We will find examples of such machines used in everyday life and we will discuss their uses. Development: Using prototypes of different models of machines a demonstration of machines at work will be presented. Students will be asked to deduct the type of work performed by each and the direction of the movement they create. Practice: Students will look at and manipulate simple and more complex tools that function on the principle of circular movement in order to observe how they work. They will be asked to list their observations in a table for further reference. Checking For Understanding: Quiz will be given at the beginning of the next class to verify understanding of machines that turn and of the related vocabulary. Closure: Recall the different machines referred to during this class and try to find examples of wheel and axle tools within the classroom, the school... Evaluation: At the beginning of class students will recall the parts of a class 1 lever (position of fulcrum, load and effort force) They will calculate the mechanical advantage of a class 3 lever and the length of the effort and load arms. Next class students will have a quiz on types of machines that turn and the way they move to perform work. They will also identify the main parts of some of these simple machines. Teacher Reflections: This topic is not always easy to understand and it would be interesting to have manipulatives to allow students to see more clearly how these machines operate to do work. I am hoping to find a video or animated pictures on the internet to complement this lesson.