Scaling & Body Metrics

 

Subject Area

 Scaling and Body Metrics
Age or Grade

 6th-8th grade
Estimated Length

 50-80 minute class period
Prerequisite knowledge/skills

 Math skills, including an understanding of ratios.
Description of New Content

 1. Scale is the size relationship between a representation and an actual object.
2. Scale models help people understand
relative size and understand relationships
when actual distances are too large or small
to deal with.
3. Allometry is the relationship between size
and shape.
4. Allometry rules enable predictions about
the size of objects and organisms with similar
shapes.
Goals

 Students will be able to calculate the scale of
a drawing. Students will be able to draw
objects to scale.
Materials Needed


 Scaling worksheet, measuring tapes

Procedure

 

 

 

Opener Talk to students about ‘Mini Me’ from
the Austin Powers movie. If they were going
to design their own ‘Mini Me’, how tall would
he/she be? How long would his/her pointer
finger be?
Procedure: 1. Draw any object on the board
(e.g. tree with branches, rectangle). Show
how to draw that object at a different scale
(e.g. 50%) by measuring the initial object on
the board and drawing the other at 1⁄2 size.
2. Have students complete an example
problem from the worksheet (attached)
3. Give students a definition for the word
‘allometry’. Explain that objects with a similar
shape have the same relationship between
parts. (e.g. adults and children humans have
the same shape- 2 arms and 2 legs- the
relative length of these limbs is the same)
4. Introduce the Body Metrics worksheet
5. Students should measure the length of
their partner’s arms and legs, as well as total
height. Have someone measure the teacher
and any other adults in the room.
6. Give students time to calculate ratios of
these body parts to overall height.
7. Discuss reasons why the ratios are close
to 1 and any potential causes of any
deviations from 1 (e.g. measurements error,
small sample sizes, children’s bodies may
grow at different rates, etc.)
Closure Remind student of the initial scaling
lesson. Have the students think of places
scaling is used in their everyday lives.

Evaluation

 Design test problems for calculating scale
and drawing objects to scale, similar to those
on the worksheet (attached).
Extensions

 1. Discuss measurements/scale of other 4-
limbed animals. Have students predict
whether ratios of animal limbs (e.g. frogs)
would be similar to those they calculated for
humans.
2. Further extend the above by measuring
actual animals (recommendations: frogs for
dissection)
References FOSS Planetary Science Course, © The
Regents of the University of California