What causes waves? Wind
Waves also occur in rivers,
lakes, and puddles.
•MYP Unit Question:
•Area of Interaction:
•Learner Profile:
•Standard:
How do we use water?
Health and Social Education
Thinker and Balanced
Recognize the significant
role of water in the
Earth’s processes.
•Learning Standard: I’m learning about currents
because they move water
through the oceans.
• Opening: Survivor IMMUNITY Challenge
• Work Session: Notes over Tides
• Closing: Tide Simulation
TIDES !!!
If it’s written in yellow, write it down.
So what
causes tides?
The word "tides" is a
basic term used to define
the alternating rise and
fall in sea level with
respect to the land.
Tides are
produced by the
gravitational pull
of the moon and
the sun.
•known for having the highest
tidal range in the world.
Atlantic Ocean
Gulf of Maine, U.S.
Tidal Bulges...
LOW TIDE
HIGH TIDE
HIGH TIDE
LOW TIDE
The water “bulges” toward the moon
because of the moon’s gravitational pull.
•Draw this image on your foldable under TIDES.
The moon at work...
• The water is pulled
toward the moon at
point A.
• The water is pulled
AWAY from the sides
perpendicular to
point A.
How often do we have high
tides and low tides?
• Let’s figure it out…
Did you figure it out?
there are 2 high tides
and two low tides each day.
In general,
Because the Earth rotates more quickly
than the moon revolves around the
Earth, tides do not occur at the same
time each day.
So why are tides
not exactly 12
hours apart?
•Since the moon
moves around the
Earth, it is not
always in the same
place at the same
time each day. So,
each day, the times
for high and low
tides change by 50
minutes.
O.K. Let’s make it simple…
• We get one high tide
every 12 hours and 24
minutes .
Spring & Neap Tides
The Moon doesn’t work alone. Remember
the Sun’s gravity also affects tides.
•SPRING TIDES The Sun & Moon may work
together to produce higher than normal
tides.
•NEAP TIDES The Sun & Moon may work
against each other to produce lower than
normal tides.
NEAP
TIDE
Lower than
normal tides
SPRING
TIDES
Higher than
normal tides
•Notice Spring & Neap tides only
occur at certain phases of the
moon.
How often do Spring & Neap
tides occur?
• Uh…I need to see
that picture again
before I can answer
that!
• I know the answer.
Let’s move on.
• Why are ocean tides so different
everywhere?
"Because they depend on many factors
including the topography of your local
coastline, and exactly where the Sun and
Moon are located.
•Closing: Tide Simulation
•Get in a “circle” and hold hands.
As the “moon” walks around behind you,
lean toward it.