Teacher Resource Guide Preferred Activities Education Outreach

Transcription

1 Teacher Resource Guide Preferred Activities Education Outreach With Generous Support from the Maxwell H. Gluck Foundation

2 Finding Your Way How do we know where we are and where we're going? Background Beginnings of Navigation Almost anyone can travel without getting lost, as long as they know where they are, where they want to go and the path between. On land, a person can use landmarks and physical descriptions: "Take the path uphill to the big rock that looks like a bear. Find the three trees growing from one stump and walk past it until you can see the waterfall." This method doesn't work well on the ocean: "Turn left at the third wave, and go until you see the big fish with the red stripes. Turn right and go until you reach England." The earliest sailors probably kept close to shore, using the land's physical features as landmarks to steer by. This worked well for short voyages, since food, water, and shelter were always dose by. Of course, this approach worked only when sailing during the day, and made for very long trips. As sailors made maps of their travels, it became evident that some places could be reached faster by sailing in a straight line, rather than hugging the shore. But this would mean leaving sight of land and any recognizable landmarks. Some of the early methods used for navigating across open waters involved using the sun, moon, and stars. People had long been travelling on land, getting from place to place by traveling in directions in some relationship to these celestial bodies. With the invention of the compass, people could find their direction even when they couldn't clearly see the sky, day or night. These methods were applied to ocean travel; if a sailor knew another port was west of his home port, all he had to do was follow the path of the sun or his compass. Unfortunately, winds and currents further complicated this process, as they could easily and subtly alter the heading and leave the traveler lost. Through generations of experience, many early coastal cultures became familiar enough with their local currents and winds to actually be able to navigate by them over moderate distances away from shore. Long distance voyages and trips to little known areas, on the other hand, were still problems.

3 Latitude and Longitude The concepts of longitude and latitude have been used now for roughly 2000 years. Lines of latitude run around the globe and measure the degrees north or south of the equator. The equator is given a value of zero (0). Lines of longitude run up and down the globe and measure the degrees east or west of a line called the prime meridian, which passes through the original location of the Royal Observatory at Greenwich, near London, England. The prime meridian is given the value of zero (0) degrees. When the latitude and longitude are given, the precise location of a point can be located on an imaginary geographic grid. When latitude and longitude are given on a map, latitude is always written first. Degrees of latitude and longitude are further divided into minutes and seconds. There are sixty minutes in one degree, and sixty seconds in one minute. One of the earliest tools used to aid mariners in determining latitude was the astrolabe. This instrument consisted of a metal disk, graduated in degrees, with a moveable sight. The astrolabe was held vertical by a plumb bob, and the navigator (with the help of two other people) adjusted the sight until it was in line with a star. The degree measurement was then looked up on charts and tables, which gave the latitude of the ship. Modifications of this instrument by scientists, including Sir Isaac Newton, led to the development of a new device called a sextant. The basic design of the sextant has remained virtually unchanged for over 200 years. Determining longitude was a bit more difficult. Many attempts were made at finding ways to determine longitude while at sea, but none were very successful. In 1735, John Harrison developed the chronometer-an extremely accurate timepiece that was used to maintain a time reference to the prime meridian. This instrument allowed navigators to compare local time to time at the prime meridian. The time difference between the navigator's present position and the prime meridian told them their position. At last, a simple and reliable method of determining longitude! It was now possible to accurately determine position anywhere on the ocean provided you had good charts and tables, and an accurate chronometer. Sailors navigated well into the 20"' century using these techniques until the advent of more sophisticated electronic and radio methods. New Technologies Today, radio beacon towers are located all along our coastlines, constantly sending out powerful identification signals. These signals can be picked up by sea vessels as far as several hundred miles away. The Radio Direction Finder (or RDF) on board a ship can be tuned to receive these broadcast signals. The beacon's I.D. signal, in Morse code, allows the navigator to look on a map and find the radio beacon that is sending that particular signal. The RDF is also used to determine the direction or heading from which the signal is being sent. A second radio beacon signal is then needed to pinpoint the exact location of the vessel. This entire process is known as triangulation. (See the activity Getting Your Bearings for more information.) The Global Positioning System (GPS) is a satellite-based radio navigation system developed in the 1970's by the Department of Defense. GPS allows land, sea and airborne users to locate their three-dimensional position any time, anywhere in the world. The CPS uses an array of satellites continuously sending highfrequency radio signals; at any given time from any point on earth, there are six or more GPS satellites orbiting above you. GPS receivers, many of which are smaller than a paperback book, are used to pick up these signals. These satellite signals contain information about the exact position and dock reading on board. The GPS unit compares the signal departure times and arrival times, and the time delay is used to calculate the distance between the satellite and the receiver. The GPS determines the distances from three or more satellites and uses this information to find the closest possible location of the user, usually within a few feet.

4 Materials large wall map* sets of activity pieces with map coordinates* tape Map Building worksheets Tape Rulers (one per student) *materials found in Seamobile Teaching Kit Activity time 40 minutes Process skills Communicating Comparing Ordering Map Building Students will develop their own map based on their knowledge of latitude and longitude and discover the many things that make up an ocean ecosystem. Connections Math Geography Procedure 1. Review the concepts of geographic grids, latitude, and longitude. 2. Explain to the students that over the years, the Seamobile research area has been mapped by many different people for different reasons. Before we can study the area, one concise map must be developed so that we know where everything is. It will be the students' jobs to piece together the information from the previous investigators. 3. Divide students into teams and distribute one set of four map pieces to each team. Each piece represents an ocean feature (kelp forest, shipwreck, sewage drain, etc.) In addition, each team (or student) should receive a map worksheet depicting the area surrounding the San Pedro Channel. 4. Using the latitude and longitude coordinates on the back of each individual map piece, students should locate the proper positions of their pieces on the map worksheet. 5. Each team representative will place their team's map pieces on the wall map using tape. In many cases, students can confirm the location of their map piece by looking on the large map for a similar symbol. 6. Discuss what their pieces represent and why these various things are found in our oceans. Extension Many of the features described in this activity have symbols which are used on ocean maps. It is important to understand that there is more than one symbol that might be used for a feature, and that some features may not be marked on a particular map. The list of symbols on the following page can be used to doublecheck latitude and longitude readings on the wall map at the end of the Map Building activity.

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6 Common Nautical Chart Symbols Shipwreck Sewer Line Radio Beacon Kelp Bed Oil/Gas Platform Lighthouse Fish Haven Dump Site Buoy Source: Chart No. 1, United States of America, Nautical Chart Symbols, Abbreviations and Terms, 1990; Department of Commerce, National Oceanic and Atmospheric Administration; and Department of Defense, Defense Mapping Agency.

7 Getting Your Bearings Students will use rulers and an understanding of compass readings to identify the location of five possible Seamobile study sites through a process of triangulation. Students will then determine headings to each of these sites. Introduction There are various ways to determine your position in the open ocean. One method is to use a Radio Direction Finder (RDF). Radio signal transmitters (beacons) are located along coastlines and send signals that can be picked up by the RDF device on ships at sea. The radio signal can then be used to determine the compass bearing from the radio beacon to the ship. By determining the bearings from two different radio beacons, navigators can determine their ship's position by examining where the bearing "lines" intersect. This method of pinpointing the location of an object based on two different bearings is called triangulation. In this activity, the Seamobile has scouted five possible study locations and has taken radio beacon readings at each of these locations. Using triangulation, the students will plot the location of the Seamobile and the five study sites. Then they will plot headings from the Seamobile to each location. Procedure 1. Divide the class into teams of 3 or 4 and distribute materials to each team. Introduce the concept of triangulation and discuss the use of radio beacons and corresponding compass headings to determine location. Distribute the "Student Information Sheet" and data table for this activity 2. Locate the Seamobile on the chart through triangulation. Use the given radio beacon (RB) readings as compass headings to plot. For example, if radio beacon one (RB1) is 90, this translates into a compass reading of 90 degrees. Follow the steps as described on the Student Information sheet. 3. It is helpful to work through the triangulation method for the Seamobile location step-by-step with the entire class. 4. Once students have identified the location of the Seamobile, they should proceed to identify the locations of each of the study sites, using the radio beacon readings in the data table for each site. 5. After the study sites have been located, the students can determine the compass heading from the Seamobile to each study site. Again, you should work through the first heading (for site A) with the entire class. Follow the steps described in the Student Information sheet. 6. Remind the students that because they are using a circle of 360 degrees to define their direction, they don't need to add a direction indicator (like S or NE). These direction designations are redundant for this method. 7. Ask students to double-check their locations by using the latitude and longitude readings from the answer key. Materials laminated desk map* (one per team) parallel ruler* (one per team) overhead marking pen* (one per team) Getting Your Bearings worksheet *materials found in Seamobile Teaching Kit Activity time minutes Process skills Communicating Comparing Ordering Connections Geometry Geography T e a c h i n g T i p : You may wish to use an overhead transparency to help demonstrate triangulation to the entire class first. T e a c h i n g T i p : A q u i c k check to see if students were able to correctly identify the location of the Seamobile is to look for a nearby depth reading of 204 fathoms on their map. If the intersection of the bearing lines is within a quarter diameter of this point, students are on the right track!

8 Student Information Sheet Getting Your Bearings The triangulation process described below will help you find the location of sites on ocean and help you figure out what direction you need to travel to get there. To locate a site 1. Locate the two radio beacons (RB1 and RB2) and the compass rosette on your map. 2. Begin by looking at one radio beacon reading (RB1) and marking the heading on the compass using the overhead marking pen. Use the parallel ruler to draw a straight line connecting your heading mark and the center of the compass. 3. Place the bottom edge of the parallel ruler along the compass line you just drew. While holding the bottom of the ruler in place, move the top half of the parallel ruler up until the ruler edge touches the center point of RB1. Use the marking pen to draw a line on the map along the top edge of the ruler. Be sure to hold the ruler so that it does not slide. 4. Remove the ruler you have just recorded your first radio beacon heading! This tells you that the location is somewhere along that line. To pinpoint the site even more, you ll need another heading (like RB2).

9 Student Information Sheet Continued 5. Repeat steps 2 through 4 for RB2. The line you draw in step 4 this time should intersect the first line. If not, try these steps again. 6. Circle the point of intersection and label it. Repeat these steps to find the other sites. To find the heading: 7. Place the top edge of the parallel ruler so that it connects the Seamobile location (SM) and a study site. While holding the top part of the ruler in place, lower the bottom half of the ruler edge until it touches the center of the compass rosette. Draw a line along the lower edge of the ruler, passing through both sides of the compass rosette. 8. To choose the correct compass reading, look at the direction you would take to get to the site from SM. If you are heading north, choose the compass reading on the north (top) side of the compass; if you are heading south, choose the south (bottom) reading. Record your heading on the data sheet. 9. Repeat these steps to find headings for the other sites.

10 Student Data Sheet Getting Your Bearings Record the headings for each site Mark the approximate location of each study site on the map below

11 Answer Key Getting Your Bearings

12 Odds and Ends Students are introduced to a common method of classification used by scientists-the dichotomous key. They will use this method to "identify" a collection of everyday objects. Introduction Scientists use keys to help identify and classify plants and animals. By organizing specimens based on similar characteristics, scientists can better understand how these species might be related to each other on an evolutionary level. Keys can come in many different formats- some are used to identify organisms into larger categories, such as kingdoms or phyla, and others are used to distinguish among closely related species. Dichotomy: Division into two parts, groups or classes. Materials Bag of odds and ends* (one per team) (Each bag of odds and ends contains: small metal paperclip, large metal paperclip, plastic coated paperclip, wooden clothespin (w/out metal spring), party toothpick w/ plastic fringe, small sponge, metal jack (colored), rubber garden hose washer, penny, plastic straw (cut to 3 ), penciltop eraser) Odds and Ends worksheet materials found in Seamobile Teaching Kit Activity time 30 minutes Process skills Comparing Ordering Categorizing A dichotomous key presents the user with a series of positive/negative statements relating to distinct characteristics of the specimen. ("The animal has a backbone.", "The animal does not have a backbone.") These statements are sometimes referred to as couplets. Notice that the couplet is essentially an either/or choice. The specimen is correctly identified when one makes the appropriate choice for each set of characteristics in a series of consecutive steps, similar to a flow chart. This activity introduces students to the use of a dichotomous key using everyday items. The goal of this activity is NOT to try to identify these objects, but rather to use a key correctly. Procedure Discuss with students different ways of grouping objects. Ask why it is important to group objects. You might Introduce dichotomous keys as one way of grouping and identifying things. Introduce the term "dichotomy" and show how this is important in this kind of classification scheme. Example: The people in this room could first be grouped into categories of eye color. One couplet for this might be: People who have brown eyes. People who don't have brown eyes. 2. Divide the students into teams of two or three and give each team a bag of odds and ends and the worksheet Odds and Ends. 3. Students should choose one item from the bag and follow the key in order to "identify" the object. After making the appropriate choice in each couplet, the team will then follow the directions on the right hand side of the key until they have identified the object with a particular letter. Students can write the object name next to the appropriate letter on their worksheet, or copy this information into a notebook. Teaching Tip: Students often "switch" their items as they proceed through the key, choosing an item that matches the positive statement. That is, a student classifying a paperclip, after the statement "Object not made of metal", might drop the paperclip and pick up a toothpick, since it makes that statement true. Ask students to close their bag after choosing an item. The bag should remain closed until the group has completely finished identifying that object.

13 Student Worksheet Odds and Ends For this activity, you will use a dichotomous key to sort some everyday objects. How to Use This Key 1. Choose one item to start with. 2. Begin by reading the first set of choices, called a couplet. After discussing the two choices within the first couplet with your team, decide which statement in the pair most closely describes the item you are trying to identify. 3. Next, follow the directions on the right hand side of the key. For example, in couplet number 1 if you decide that the object was metal, you would continue on to couplet number 7; if you decide that the object is not metal, you would continue on to couplet number Continue to work until your team has identified all 11 objects. 5. After you have identified all the objects, check your answers with the teacher's answer sheet. choices 1. Object made of metal Object not made of metal 2. Wood Not wood 3. Plastic tip No plastic tip 4. Rubber Not rubber 5. Pointed Not pointed 6. Rectangular shape Tube shape 7. Painted Not painted 8. Flat Not flat 9. Object copper color Object silver color 10. Greater than 3 cm Less than 3 cm directions Go to couplet 7 Go to couplet 2 Go to 3 Go to 4 Object a Object b Go to 5 Go to 6 Object c Object d Object e Object f Go to 8 Go to 9 Object g Object h Object i Go to 10 Object j Object k

14 Answer Key Odds and Ends Object a Object b Object c Object d Object e Object f Object g Object h Object i Object j Object k tooth pick clothes pin eraser rubber washer sponge plastic straw painted paper clip jack penny large paper clip small paper clip

15 A Key to California Marine Shells Students will use a dichotomous key to identify a collection of shells from local marine animals. Procedure 1. Divide the students into teams of two or three. 2. Give each team of students a set of unidentified marine shells, from the Teaching Kit. 3. The student worksheet describes how the key should be used. When students have finished identifying the shells, they may check their answers on the answer sheet provided. Extension Ask students to create a simple diagram that shows how they grouped the shells. Remind the students to describe the characteristics at each branch point. (See sample below.) shells Materials Set of marine shells* (one per student team) A Key to California Marine Shells worksheet *materials found in Seamobile Teaching Kit Activity time 30 minutes Process skills Observing Comparing Ordering Categorizing two parts one continuous part round or circular clam

16 Student Worksheet A Key to California Marine Shells This dichotomous key will allow you to identify 8 shells from southern California. Follow the directions below to correctly identify each species. How to Use This Key 1. Choose one shell to start with. 2. Begin with the first set of choices, called a couplet. 3. After discussing the two choices in the first couplet with your partner, decide which characteristics in the pair most closely resemble the shell you are identifying. 4. Next, follow the directions on the right hand side of the key. For example, in couplet number 1 if you choose that "the shell has one part", you would continue on to couplet number 3; if you choose that "the shell has two parts", you would continue on to couplet number After you have identified each shell, check your answers on the answer key. Pair Couplets Directions 1. Shell has two hinged parts Shell has one continuous part Go to couplet 2 Go to couplet Each shell is teardrop shaped or oblong Each shell is round or circular Shell has one hole or opening Shell has more than one opening Mussel Clam Shell is 6cm or smaller Shell is 6cm or larger Shell is purple-gray Shell is brown-orange Total length of shell is 8cm or smaller Total length of shell is 8cm or larger Shell has four or more small holes on top Shell does not have four or more small holes on top 5 6 Olive snail Chestnut cowry Wavy top turban snail Kellet's whelk Abalone Keyhole limpet

17 Answer Key A key to California Marine Shells clam Mussel chestnut cowry olive snail (olivella) Kellet's whelk keyhole limpet abalone wavy top turban snail