This week we are taking a look at another one of the six simple machines, the pulley. This will be a two week investigation on pulleys. Pulleys are useful simple machines because they transfer the direction of force needed to lift an object and can give us a mechanical advantage (depending on the type of pulley that is used). There are different types of pulleys: fixed, moveable, and compound, such as the block and tackle pulley. Fixed pulleys are just that - they are fixed in position and do not move except to have their wheel spin. These are usually found on blinds, curtains, flag poles, wells, and on cranes. Moveable pulleys move with the objects they are lifting or moving, such as zip lines, hoists, elevators, cable cars, and sky rides. Moveable pulleys can give a mechanical advantage because it requires less effort to lift or move an object than with fixed pulleys. Like compound words and machines, compound pulleys are made up of two or more pulleys, or pulleys that use two or more wheels. Compound pulleys like a block and tackle pulley can be found on sailing boats, shipping vessels (like fishing boats), tow trucks, and engine hoists.
The students have been exploring some of the different types of pulleys using wooden models. We have also explored the school and found some pulleys that help us with tasks like pulling the American flag up and down the pole each day, opening and closing the curtains on the stage, and opening and closing the blinds (or drawing the blinds across the window). We watched a video clip from PBS's "Sid the Science Kid"series as Sid learns about a simple machine that can help him move some of his toys up to his newly built tree house. (Next week we will watch the conclusion of the video and see some other ideas and examples of pulleys that Sid and his friends and family come up with.) In our journals, we have been drawing some examples of pulley systems and blueprinting the direction of effort used, and how it is being used to make our lives easier.
The fourth and fifth graders started exploring pulley systems using single, double, and triple pulleys, spring scales, and washers. They have been constructing pulley systems to move large washers and investigating the mechanical advantage they get with each system.
Friday, March 9, 2012
Thursday, March 1, 2012
Inclined Planes Help us Move
This week we are taking a closer look at inclined planes and how they help us move. An inclined plane is a flat surface that has been raised at one end, such as a ramp, slope, or slide. Stairs can be considered an inclined plane because they help to move loads gradually rather than straight up or down. There is a trade off, though, in using an inclined plane to help move a load, you are trading force for distance. It will take less force to move an item up a ramp into the back of a truck, for example; however, it will require more distance to go up the ramp rather than a straight upward lift, like from the side walk directly below into the tailgate of a truck.
The primary students have been exploring inclined planes through Legos and building water slides for the balls or Lego people to go down. The students enjoyed working in small groups to design their slides with little direction from me, except what an inclined plane is, and what their slide had to do. (Although, for some, I did have to provide a little additional guidance about connecting the tubes together so they fit in the doorways.)
The intermediate students have been conducting experiments in distance and force using cars and car launchers they made from the Legos. We have been able to tie this lesson in with math, and for some, this is an introduction to the metric system, in using meter sticks to measure the distance the cars are launched. The students also had to construct a data table in their journals to record the varying distances with the launchers, then analyze the data, and discuss their results - both verbally and in writing.
For more information about inclined planes as part of simple machines, check out these sites:
The primary students have been exploring inclined planes through Legos and building water slides for the balls or Lego people to go down. The students enjoyed working in small groups to design their slides with little direction from me, except what an inclined plane is, and what their slide had to do. (Although, for some, I did have to provide a little additional guidance about connecting the tubes together so they fit in the doorways.)
The intermediate students have been conducting experiments in distance and force using cars and car launchers they made from the Legos. We have been able to tie this lesson in with math, and for some, this is an introduction to the metric system, in using meter sticks to measure the distance the cars are launched. The students also had to construct a data table in their journals to record the varying distances with the launchers, then analyze the data, and discuss their results - both verbally and in writing.
For more information about inclined planes as part of simple machines, check out these sites:
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