Students can create a simple machine as part of a physical system project.
Science teachers have a wonderful opportunity, when they teach third graders, as they are genuinely curious and keen to experientially learn about the world around them. Grade three science curriculum covers three types of systems: living systems, how organisms interact with their environment and other creatures; earth systems, how planet Earth interacts with the atmosphere, hydrosphere, biosphere, geosphere and other components of the solar system; and physical systems, such as energy, motion and machine systems.
Local Ecosystem
Third grade students can complete a science project on a real-world ecosystem. They should choose an ecosystem close to their home or school, such as their backyard, a local pond, the zoo or a nearby park. Encourage students to make observations of what lifeforms, both plants and animals, they observe. Observations may come in the form of sightings, sounds or visual clues, such as animal tracks and or dens. As a culminating activity, students can complete either a food chain or a food web, consisting of multiple chains representative of the ecosystem. They can add some artistry that goes beyond connecting words with arrows. For example, if one student includes a food chain consisting of a squirrel that eats acorns, he could glue cracked acorns to his food web poster board. If a student observes a pet cat or a raccoon's tracks outside, he can sketch them, take a picture of them or even take a plaster casting of them and include this as part of one of the food chains. He can then extend an arrow to what this animal eats, such as a cat eats a mouse which eats seeds or a raccoon eats baby birds which eat worms.
Simple Machines
In third grade, students start learning about physical systems, such as simple machines. With the help of a parent or older sibling, they can build their own simple machine. The six simple machines are the pulley, the lever, the inclined plane, the screw, the wedge and the wheel. It is important for students to understand how each component of the machine interacts to produce the desired power or energy. Provide the opportunity for students to explain how each component of the machine plays a role, either through a verbal or simple written explanation.
The Water Cycle
One earth system that third grade students study is the water cycle. Students can visually demonstrate the water cycle in a variety of ways to show their understanding and knowledge about the system. Students should understand that all of the Earth's water sources are interconnected and are affected by the Sun, the atmosphere, the Moon and other universal factors. They could create a diagram that includes lakes and oceans, the Sun, clouds, groundwater, runoff, precipitation and evaporation. Other ways to show the water cycle are to create a slide show, a three-dimensional model or to act out a demonstration with other classmates.
Plant Experiment
Third graders are expected to practice the scientific method by performing an experiment. In order to better understand which aspects of a living system a plant depends on for survival, students can design their own experiments to determine a plant's optimal growing conditions. For example, students can grow plants in sunlight, shade and darkness, grow their plants in different mediums, such as organically rich soil, clay and sand, or water them with pure water, salt water and juice. Students should write an hypothesis of which plants will grow the most successfully, record their observations, measure their plants regularly and come up with a conclusion. They should also familiarize themselves with the basics of photosynthesis.
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