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Lesson 1 Guide: Location

Activities

Tools of the Ancients -- making instruments and measuring latitude and longitude
A Place in Time -- documenting changing characteristics using maps

Link to Lesson 1: Location

Notes

This lesson explores the methods of characterizing places, from the five senses to sophisticated tools of measurement. Every place has important characteristics and a unique location relative to other places. Latitude and longitude measurements indicate a place's absolute location on the globe.

Tools of the Ancients has students make a sundial and an instrument similar to a sextant. The students translate observations from these instruments into latitude and longitude.

A Place in Time has students document the history of a place. Students do research, organize information, and make maps and a timeline for a place of their choice.

Glossary

dead reckoning	The estimation of a ship's position from the distance according to the ship's log and the course steered by the compass, with corrections for currents and other factors, but without astronomical observations.
Greenwich time	Mean solar time of the meridian of Greenwich, England, used by most navigators and adopted as the basis of standard time throughout the world.
landmark	Any prominent object on land that can be used in determining a location or direction.
latitude	Angular distance measured in degrees, minutes, and seconds north and south to the geographic poles from the equator.
longitude	Angular distance measured in degrees, minutes, and seconds 180 degrees east and west from the Prime Meridian, the imaginary north-south line through Greenwich, England.
magnetic compass	an instrument having a magnetic needle to indicate magnetic north.
mappa mundi	From two Latin words meaning tablecloth and world, a graphic or verbal representation of the world as understood in the Middle Ages in Europe.
marine chronometer	A portable timekeeper with a special mechanism for ensuring and adjusting its accuracy, for use in determining longitude at sea.
photogrammetry	The techniques used to obtain reliable measurements from photographs.
planetable	A device for plotting survey data directly from field observation. Consists of a drawing board on a tripod with a sighting instrument to measure and plot angles.
planisphere	A projection or representation of the whole or part of a sphere on a plane.
portolan chart	A type of sea chart common in the Middle Ages that was used for navigation at sea. Characterized by rhumb lines, or lines of constant compass heading, and the names of ports. From the Italian, portolano, a collection of sailing directions.
remote sensing	The process of detecting or monitoring the properties of an object without physically contacting the object.
sextant	An astronomical instrument for measuring angles, primarily altitudes of celestial bodies, to determine latitude.
surveying	The techniques used to make measurements in space to determine the relative positions of map features.
theodolite	A precise surveying instrument having a telescopic sight for measuring horizontal and vertical angles.
triangulation	A method of surveying in which the stations are points on the ground at the vertices of a chain or network of triangles. The angles of the triangles are measured instrumentally and the sides are derived by computation from selected sides or bases, the lengths of which are obtained by direct measurement on the ground or by computation from other triangles.

Answers to questions

Tools of the Ancients; Columbus...
Extension 1	Students will observe slightly different values; this is normal. The range of values will vary. The "best" value is probably an average (the sum of observations divided by the number of observations).
Extension 3	Columbus might not have decided to sail west, since the trip to the Orient would have been so long. Spain's monarchs, Ferdinand and Isabella might not have sponsored a trip that risky.
Extension 4	The analemma shows two kinds of information (1) how high the Sun is in the sky on each day of the year at noon local time on the meridian on which the analemma is centered; and (2) the difference between solar noon time and standard noon according to the clock. The analemma can be placed on any meridian. Apparent changes in the height of the Sun in the sky result from the tilt of the Earth's axis of rotation. The tilt is constant, but at different positions in the Earth's orbit around the Sun, the changing effect causes the seasons. Variation in day lengths is the combined effect of three factors. The speed of the Earth in its elliptical orbit varies. This effect combined with the effects of the tilt of the Earth's axis of rotation and the counterclockwise direction of rotation and revolution produces the variations in local noon shown on the horizontal axis of the analemma.

Tools of the Ancients; Local Time...

Instruction 6 The sun is at its highest when the shadow is shortest. The clock time of this observation differs to the east and west. As the Earth rotates toward the east, local noon time is earlier in the east.

Extension 1 The angular difference between geographic north and magnetic north is the difference between the direction indicated by the sundial at local noon and the direction to north as indicated by a compass needle. Geographic north is the north end of the Earth's axis of rotation. Magnetic north is the north end of the Earth's magnetic field.

Extension 2 To determine the number of degrees in a time zone, divide 360 degrees by 24 hours (360/24=15). To calculate your longitude knowing the time difference from Greenwich, multiply the number of hours difference by 15 degrees. For example, if the time in Greenwich is 6 hours ahead of the time where you are, your approximate longitude is 6 x 15, or about 90 degrees west of Greenwich.