Unplugged Activity: Classroom Coordinates

In this activity, students will practice to familiarize themselves with the difference between relative coordinates and absolute coordinates in your own classroom. How general or detailed you choose to be with coordinates depends on the age and skills of your students.

Materials

• Masking tape or painter’s tape (optional)
• Index cards or labels
• Graph paper (optional)

Setup: Identify which direction or wall of your classroom represents each of the four cardinal directional points - north, south, east, and west - and label them as such. If you can, place masking tape on the floor to represent the X-axis and Z-axis, creating a coordinate grid with the origin at the middle point of the room where these axes meet. This works especially well if you have a tiled floor. Remind the students that the Y-axis is the vertical up/down axis.

Student absolute world positions

1. Imagine that your classroom is a Minecraft world of its own.
2. Place at the origin point a sign indicating the classroom world position (0, 0, 0).
3. Stand on this origin point.
4. Ask the students to write down on an index card or paper their classroom world position in the format (X, Y, Z). In other words, from the origin point, how would you need to travel along the X and Z axes to reach where they are? (If your floor is not tiled, use a step to represent one block.) For this exercise, have them leave the Y coordinate as zero (0).
5. Check a few students’ world positions by walking from the classroom world origin point to each student to make sure they are correct.

Example: A student gives her or his classroom world coordinates as (4, 0, 2). If you walk four steps (or tiles) east and then two steps south from the classroom world origin point, you should end up where they are sitting.

To discuss:

• Which coordinate will be the same for all students? (Y)
• What determines an average step?
• What is the margin of error for short distances?
• What is the margin of error for large distances?
• Why isn’t this a problem in Minecraft itself?

Object absolute positions

6. Pick an object in the room that has a permanent place.
7. Ask the students to identify this object’s classroom world position and label it.
8. If the object is off the floor, have the students give the Y coordinate as something other than 0. (You will want to set a consistent vertical measurement, such as 1 foot = 1 block.)

Repeat the previous steps with other objects that have a permanent place in the classroom – for example, the wall clock, the door to the classroom, or a window. Have the students label these objects with their respective world positions. When you feel that the students have mastered the concept of absolute world position, move on to the next section.

Student relative positions

1. Remind the students that with relative positions, the origin (~0, ~0, ~0) is where they are.
2. Point out an object in the classroom that was labeled with an absolute world position in the previous exercise.
3. Ask students to write down on an index card or paper how far and in which of the cardinal directions (north, south, east, or west) they would need to travel from where they currently are in the classroom to reach the object. They should use the format (~X, ~Y, ~Z).
4. Have the students move to a different place in the room and then recalculate the object’s position relative to their new positions.
5. Repeat the previous step with other objects that have a permanent place in the classroom.

Point out the differences between an absolute classroom location and a relative position:

• The absolute position of an object with a permanent place does NOT change.
• The position of an object relative to a student’s position changes as the student moves around the classroom.

Additional Challenge: Relative position of moving objects

1. Have students work in pairs to calculate their partner’s position relative to their own position.
2. Have both students then move around and recalculate their positions relative to each other.