We begin our foray into the Core Knowledge scope and sequence with a unit on:

Gravity

• Gravity: an attractive force between objects
Newton’s law of universal gravitation: Between any two objects in the universe there is an attractive force, gravity, which grows greater as the objects move closer to each other.
How gravity keeps the planets in orbit

Following the Core Knowledge scope and sequence we will focus on:

Astronomy: Stars and Galaxies

• Stars
The sun is a star.

Kinds of stars (by size): giants, dwarfs, pulsars
Supernova; black holes
Apparent movement of stars caused by rotation of the earth Constellations: visual groupings of stars, for example, Big Dipper, Orion Astronomical distance measured in light years

• Galaxies
The Milky Way is our galaxy; the Andromeda Galaxy is closest to the Milky Way. Quasars are the most distant visible objects (because the brightest).

Plate Tectonics

• The surface of the earth
The surface of the earth is in constant movement.
The present features of earth come from its ongoing history. After the sun was formed,matter cooled creating the planets. The continents were once joined (Pangaea).

• Layered structure of the earth

Crust: surface layer of mainly basalt or granite, 5 to 25 miles thick Mantle: 1,800 miles thick, rock of intermediate density, moves very slowly Outer core: liquid iron and nickel
Inner core: solid iron and nickel, 800 miles thick, about 7,000 degrees C

• Crust movements
The surface of earth is made up of rigid plates that are in constant motion.
Plates move because molten rock rises and falls under the crust causing slowly flowing  currents under the plates.
Plates move at speeds ranging from 1 to 4 inches (5-10 centimeters) per year. Earthquakes usually occur where stress has been built up by plates moving in opposite directions against each other. Earthquakes cause waves (vibrations) which have:

focus, the point below the surface where the quake begins

epicenter, the point on the surface above the focus
Severity of ground shaking is measured on the Richter scale

• Volcanoes usually occur where plates are pulling apart or coming together, but some occur  at holes (hot spots) in the crust away from plate boundaries. As plates move over these  hot spots, they cause chains of volcanoes and island chains like the Hawaiian Islands.

• Evidence for long-term movement of plates includes fit of continents and matches of rock types, fossils, and structures; ocean floor age and topography; ancient climate zones; locations of earthquakes, volcanoes, and mountain ranges; magnetic directions in ancient rocks.