MAKE YOUR OWN RULER

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MAKE YOUR OWN RULER
INTRODUCTION
Units are extremely important in measurements. Without consistent units, it would be
impossible to replicate an object in production or truly know the length, mass, volume,
or temperature someone intends. Units are a way of communication, but they are also
arbitrary. There is not one correct system of measurement. However, there are certain
requirements for any system to be considered viable. It must have at least one defined
unit for every independent physical property – length, mass, temperature, charge, etc.
These units must have a defined standard that is generally available to everyone who
needs to use the units.
In this activity, students will be creating their own system of units, beginning with length
and including at least two other physical properties. Using an unmarked straightedge,
students choose an object as their reference (ex: the length of a finger, width of a piece
of paper, the height of a cup, etc.). They will then choose an original name for their unit,
for example, ‘grenlen’ for the length of a finger. They can then subdivide or create
multiples of the unit and either make new names for those or use prefixes (made up or
SI).
Students should be encouraged to give reasons for their unit choices, such as the ease
of mathematical manipulation, like SI, or their use of objects that are accessible or easily
standardized (locally), for example, using a bottle of water for a unit weight or the
height of a table as a unit of length.
After students have created their own rulers, they will go around the classroom or
school making measurements with their system. They should then convert between
different increments (If there are 14 grenlens in a hooga, how many grenlens is this 4
hooga and 7 grenlen desk?). If possible (with balances, or other tools) they should
measure using their non‐length units as well.
Finally, after students have made some measurements, they will trade rulers and
measurement data with students in other teams. They will use the other teams’ ruler
and data to try to show the class how long some of the measured objects were without
looking at the object.
LEARNING GOALS
At the end of this activity, students should be able to:
• Recognize the need for a convenient, standardized measurement system and what
constitutes such a system.
• Understand that the size of objects needs to be expressed with suitable units and
scales
• Understand the importance of units as a way to communicate to people lengths
which have not been seen firsthand.

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MATERIALS
• A ruler
• A reference unit (ex: length of a finger, width of a piece of paper, height of a cup,
etc.)
• 5 objects for measurement. Some examples:
o Length of a cell phone
o Width of a pencil
o Size of the tip of a pencil
o Circumference of a basketball
o Length of the teacher’s left foot
• Long piece of paper (calculator paper)
• Scissors
PROCEDURE
PART ONE
1. Split the students into groups of 3 or 4
2. Have a student obtain a ruler
3. The students will now create their own reference unit. This unit can be based on
anything. The only condition is that the units cannot be based on units that already
exist like meters or inches.
4. Encourage them to come up an original name for the unit as a group. Have the
students measure the reference unit with the ruler and mark this length of the piece
of paper.
5. Have them use the ruler to make repeats of the unit.
6. Using scissors cut out the entire length of the reference unit with its repeats.
Repeated units can have new names (ex: 12 inches = 1 foot, 3 legers = 1 widget)
7. Subdivide the units and come up with a new name for the smaller units
8. Have groups define two other units that relate to different physical properties.
9. Measure the 5 objects with the new ruler. Record the lengths on the worksheet
with units
PART TWO
1. After the students have recorded the lengths onto the worksheet, exchange
worksheets with another group in the classroom.
2. Using the ruler and data given, the other group will try to show, with their hands,
arms, or by standing apart from one another, how long some of the measured
lengths were.
3. The ruler’s original group will verify their findings.

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MAKE YOUR OWN RULER WORKSHEET
Reference Unit:
Length of reference unit
Names of Multiples and/or subdivisions (ex: 5 posts = 1 leger, 3 legers = 1 widget)
Object
Measurement – Numbers and
Units
Express two of your larger objects as using your smaller unit. For example, in the metric
system, an object that is measured 3 meters and 25 centimeters is 325 centimeters
long.
Express two of your smaller objects using your larger unit. For example, a pencil that is 5
inches long is 0.417 feet long.

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DISCUSSION QUESTIONS
PART ONE
Ask the class how long one of the objects they measured was. Compare one group’s
system of measurement with another group’s. What differences can be seen?
Pair the groups and ask one group to look at another group’s measurement data. Can
they guess what the reference unit is?
Have each pairing try to come up with conversions factors between the groups. For
example, if one group said the door was 16 legers, and another group said the door was
20 knuts, then the conversions factor is 16 legers/20 knuts or 4 legers/5 knuts.
Have each group explain their choice of units to the class.
PART TWO
Why were you able to find the length of something using someone’s ruler which you
had never seen before?
The units were standardized between the two people, and so they could effectively
communicate with each other.
If two people were building different parts of a machine on opposite sides of the world,
why are they able to make pieces that fit together perfectly?
They share a common system of units, and can communicate the required or provided lengths
to each other.