PWC 3.5.1
SOL 3.8 The student will investigate and understand basic sequences and cycles occurring in nature.  Key Concepts include:

• Night and day
• Seasonal Changes 
• Phases of the Moon and Tides

Critical Attributes:

• Objects and events on Earth can change.  Some changes are slow and others changes are fast.  Some changes occur in patterns and happen over and over again in cycles.  Cycles of day and night, the seasons, and phases of the moon can be observed and described.
• The daily change from day to night is caused by rotation, or turning, of the earth.  As the Earth rotates, parts of it move into and then out of the sun's light.  The length of one day is about 24 hours.  This is the amount of time it takes the Earth to rotate once on its axis.
• The changes in seasons during a year are caused by the tilting of the Earth and by its movement around the sun.  Because the Earth is tilted, some parts of it get more direct sunlight during the day at certain times of the year than other parts, causing that to experience summer.  The other part is getting less direct sunlight and experience winter.  As the Earth continues to move around the sun, the parts experience experience alternating seasons.
• The change in the way the moon appears is also due to a cycle.  The moon is a satellite of Earth, moving around it.  It take about 29 1/2 days (or about a month) for the moon to move around the Earth.  The moon does not shine by its own light but reflects light from the sun.  Depending on where the moon is in it's orbit, we see varying illuminated portions of it.  This appears to give the moon different shapes at different times of the month.  The different shapes of the moon are lunar phases.  The lunar phases are new, crescent, quarter, gibbous and full.
• Tides, the rise and fall of the ocean waters, are caused by the gravitational pull of the moon and the sun.  This pull causes the water to draw up (high tide) on the side of the Earth facing the moon and on the opposite side.  The areas between those two points experience low tides.  As the Earth rotates, locations of the Earth expericence different tides.