Science

Science pages cover the standard upper elementary topics, with the diagrams and tables that make them easier to hold onto, and self-check questions at the end.

Third grade

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  Third grade · Science

  Heat and light

  Both are forms of energy that travel. Heat moves three ways, and light moves in straight lines until...

Fourth grade

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  Fourth grade · Science

  Animal adaptations

  An adaptation is a trait that helps an animal survive where it lives. It is inherited, not decided.

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  Fourth grade · Science

  Electric current and simple circuits

  A current is charge on the move, and it only moves when the path it travels is unbroken. Everything...

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  Fourth grade · Science

  Forces and motion

  A force is a push or a pull. Nothing changes its motion unless the forces on it are unbalanced.

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  Fourth grade · Science

  Human body systems

  Each system has one job. What makes the body work is that no system does its job alone.

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  Fourth grade · Science

  Simple machines

  A simple machine does not create energy. It changes the size or the direction of a force, and it always...

Fifth grade

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  Fifth grade · Science

  Animal growth and reproduction

  Life cycles differ enormously, but every one is a way of getting from one generation to the next with...

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  Fifth grade · Science

  Astronomy: the earth, moon and sun

  Rotation gives day and night. Tilt gives the seasons. Almost every mistake in this topic comes from...

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  Fifth grade · Science

  Climate

  Climate is the long-run pattern, not today's sky. Latitude, altitude, distance from the sea and ocean...

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  Fifth grade · Science

  Energy flow through an ecosystem

  Energy enters as sunlight and leaves as heat. Most of it is lost at every step, which is why food...

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  Fifth grade · Science

  Extinction

  A species is extinct when its last member dies. Most species that have ever lived are extinct, and the...

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  Fifth grade · Science

  Minerals, rocks and soil

  Minerals are the ingredients and rocks are the mixture. The three rock types are defined by how they...

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  Fifth grade · Science

  Natural cycles

  Matter cycles and gets reused. Energy flows through once and leaves. Keeping those two straight...

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  Fifth grade · Science

  Organisms in an ecosystem

  Every organism in an ecosystem has a role and an address. The role is its niche, the address is its...

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  Fifth grade · Science

  The earth's crust and landforms

  Two opposing processes shape every landscape. Plate movement builds land up, and weathering and erosion...

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  Fifth grade · Science

  Weather: air masses, fronts and instruments

  Weather is what the atmosphere is doing now. Almost all of it starts with the same fact: the sun does...