Using Coordinates

Est. Class Sessions: 1–2

Developing the Lesson

Introduce Mr. Origin. Mr. Origin is used to help students understand how to use coordinates (ordered pairs) to describe distance and location in the real world, on maps, and with graphs. To introduce Mr. Origin to the class, have students read the Using Coordinates pages in the Student Guide.

Use these or similar discussion prompts to begin a class discussion:

How can you tell the difference between Mr. Origin's right hand and his left hand? (Possible responses might include: Mr. Origin's right hand is different because it is larger. Or Mr. Origin's right hand is wearing a glove so you can tell the right from the left hand.)
How can you tell the difference between Mr. Origin's front and his back? (Possible response: Mr. Origin has buttons on his front.)
Why is it important to be able to tell the difference between Mr. Origin's front and back and his left and right? (Possible response: You need to know these things so you can place him correctly on the map and use him to find the location of things on the map.)
What are the four basic directions for Mr. Origin? (The four basis directions are left, right, front, and back.)
How does Mr. Origin help you find the location of an object on a map? (Mr. Origin tells you where you start when you are trying to locate something on the map.)

The fundamental idea is that students can find all directions and distances relative to Mr. Origin rather than relative to themselves. The Using Coordinates pages also introduce students to locating objects using left/right (x) and front/back (y).

The Origin of Mr. Origin. The name Mr. Origin is derived from the mathematical term “the origin,” which is the name given the point (0,0) on the coordinate plane. Students can think of Mr. Origin as specifying the place where we “begin measuring” coordinates.

Use Questions 1–3 in the Student Guide to check for understanding. To answer Question 1, students can describe the location of the globe by saying that it is between the wastebasket and Elizabeth's desk. Using Mr. Origin as the starting point in Question 2, the globe is five steps to the right of Mr. Origin and four steps to the front. As an ordered pair, students can write (5, 4). It is important to note the unit of measure in some way. On the map in the Student Guide, the fact that the measurements are in steps is noted on the scale.

Assign Check–In: Questions 1–3 on the Practice with Coordinates page in the Student Activity Book. Students complete these questions independently, using coordinates to label the location of objects on a map and placing items on a map when given their coordinates.

Use the Practice with Coordinates page in the Student Activity Book to assess students' abilities to find and map the location of objects on a map given their coordinates [E4] and identify the location of objects on a map using coordinates [E4].

Use the Find the Panda game in the Student Activity Book to provide targeted practice with these expectations.

Classroom Treasure Hunt with Mr. Origin. After you have introduced Mr. Origin and students have had opportunities to practice finding objects on a map, tell them that you found a note from a clever pirate that tells where a treasure is hidden in the room. Show students the Treasure Hunt Note page that you prepared before the lesson. Read the message from Pirate Jack out loud or ask one of the students to read the message to the class. Ask students to work with their partner to decide what the clues Pirate Jack left could be.

The discussion prompt can be used to help them begin talking with their partner:

Read the clue again and think about what information might be missing from Pirate Jack's note that can help you find the treasure. Think about two questions you could ask that will give you information you might need to find the treasure.

Provide time for students to work with their partners to formulate questions on their own. Encourage them to use their Student Guide as a resource to help guide their thinking. As student groups work, these discussion prompts can be used to provide support as needed:

Ask:

What do you think would happen if each of you used your desk as the starting point for finding the treasure? (We would all end up in different places.)
Look back in your Student Guide. How did Elizabeth and Frank know where to start counting? (They started counting at Mr. Origin.)
What is one thing you need to know to find the treasure? (You need to know where Mr. Origin is to know where to start.)
What else do you need to know about Mr. Origin? (You need to know which way Mr. Origin is facing.)
What questions can you ask to get the clue about Mr. Origin? (Where is Mr. Origin and what way is he facing?)

Provide students with the first clue by placing Mr. Origin in the appropriate place.

Continue the discussion by asking:

Now that you know the location of Mr. Origin and the direction he is facing, what other information will you need to find the treasure? (You need to know the unit of measure that Pirate Jack used to hide the treasure.)
What question can you ask to get the second clue? (What unit of measure did Pirate Jack use when he hid the treasure?)

Give students the second clue, telling them what the unit of measure will be for the treasure hunt.

Have a student use the coordinates in the Treasure Hunt Note to measure from Mr. Origin. He or she will find Pirate Jack's Message and read it aloud to the class. Using the coordinates written in the new message, students can find the treasure by measuring with the correct units to the right and in front of Mr. Origin.

If you have a room with a tile floor, you can use the length of a tile as your unit of measure, thereby recreating Descartes' original inspiration. (See Mathematics in this Unit.)

Student Guide: 324 325 326

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