| Third Grade
A Day at the Outdoor Lab
Simple Machines
On this day students spend the morning learning about the six simple machines – Inclined Plane, Lever, Pulley, Screw, Wedge, Wheel and Axle. We start with an introduction at the cottage showing an example of each. A pledge is next – a student is hoisted up the flagpole with a pulley and we do the “simple machine pledge.” Students are then divided into smaller groups and led on a leisurely hike from station to station. At stations students use simple machines to do work. Every student will get picked at least one time during the day. The stations are a combination of:
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A wedge is struck with a hammer (lever) to separate two heavy logs. The log is returned to its’ original position with a pry bar (lever).
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A car is lifted with a screw jack.
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Students compare the amount of force required to move three different shaped wheels and axles – square, hexagon, and circle. Force is measure in number of third graders needed to pull a wheel.
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Two examples of a lever are used to pick up and move a student. One is a native Indian tool; the other is a modern wheelbarrow. Both work the same with the lever’s fulcrum on the ground, the load (lifted student) in the middle, and the force (students lifting) at the opposite end.
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Students use three sets of block and tackles (paired pulleys) to lift the teacher. They compare two, four, and six pulleys to discover that it takes less force to lift as more pulleys are added.
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Students attempt to lift the teacher with a large movable lever. The fulcrum is in the middle. The closer the fulcrum is to the load (teacher), the less force (# of third graders) it takes to lift the load.
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Students take a sample of soil with a screw sampler. A wedge at the end cuts the ground.
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Lab staff person demonstrates the use of a chainsaw and/or wood splitter. Both use wedges to do the work.
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Students race in pairs to get over the hay wagon and to the other side. One line of students has the advantage of using ramps (inclined plane).
Animal Lab
The afternoon is filled with a visit to the ”Lab” to learn about Native Virginia animals. The emphasis is on reptiles and amphibians. Students are shown live captive animals and learn where they live, what they eat, and how protect themselves from being eaten. The students remain seated until we let them walk around the Lab and look in cages and take turns petting a salamander or holding a snake, toad, or turtle.
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