John Paderi
GK-12 Size and Scale Lesson Plan
Introduction to effects of size and scale on properties and phenomena
Grades 8-12
Key Words: mass, volume, density, surface area, gravity, drag, dissolution
Background: The ratio of surface area to volume dramatically increases as objects
decrease in size. Certain forces that are dominant at a large size scale can therefore be
ignored at a significantly smaller size scale, and vice versa.
National Standards
Physical Science: Content Standard B:
As a result of their activities in grades 5-8, all students should develop an
understanding of
• properties and changes of properties in matter
Arizona State Standards:
Strand 5: Physical Science
• Concept 1: Structure and Properties of Matter
 PO 1. Describe substances based on their physical properties
Overview:
With the use of various senses, students experience differences in properties of
substances when compared between nano and larger scales.
Objectives:
 Use size and scale as a unifying theme for concepts in science and math, as well
as an introduction to nanoscale science
o Molecules and matter
o Chemical reactions
o Physical forces
 Gravity, drag, evaporation, electrostatic
o Biological concepts
 Sensory
 Size limitations
 Demonstrate phenomena of size and scale that can be appreciated with different
senses
 Introduce surface area and volume as a function of size
 Incorporate simple math calculations and graphing skills to help explain physical
phenomena
Lesson Outline:
 Demonstrations with senses
o Sight
 Spray bottle – water droplets and mist


Spray water into the air such that large droplets as well as
smaller mist come out of the nozzle. When this is done in
the light, such as an overhead projector, the large droplets
falling quickly to the ground and the mist remaining in the
air are very easily observed.
 Concepts include how gravity becomes less dominating,
and the drag of air (molecules in air interacting with water
molecules) is dominating at the smaller size. At the
molecular level, water molecules become a part of the air,
unseen to us.
Alka-Seltzer – reaction time
 Take tablets and ground up tablets. Observe what happens
when you put each into a cub of water. The reaction of the
ground up tablets will happen much faster than the whole
tablets.
 Dry ice and ground dry ice will have the same result as an
alternative.
o Touch
 Corn meal – corn starch
 Take corn meal, and pulverize it in a food processor so that
it is essentially corn starch (very obviously the exact same
material, only at a different particle size). Have the
students put their hand into a bag of each to see how it feels
and how much sticks to their skin.
 Concepts include sensory differences, surface area, and
gravity. Greater surface area in powdered corn starch is
available to interact with the skin, making more particles
stick. Particles sticking to the skin goes along with the
force of gravity becoming less dominant at the smaller
scale. The sensory difference is that the powdered material
feels smooth and soft compared to the larger corn meal
particles.
o Taste
 Sugar and powdered sugar
 Take granulated sugar, and again pulverize in a food
processor so that it is obvious that the material is the same.
Have students weigh out 1 gram of each and place them
separately on the tongue of a blindfolded student. Make
sensory observations for each type of sugar.
 Concepts include sensory differences due to the number of
nerves activated on the tongue, which is greater in the
powdered sugar, as the same mass can activate more nerves
since it has a much larger surface area.
o Smell
 Cinnamon – a stick will not have as high a surface area as ground
up powder for molecules to essentially evaporate or sublime into
the air, where they can reach the nose
 Take a block, and grind it into smaller pieces – putting
20cm from your nose smell each and make sensory
observations
o Sound
 Rubber band stringed instrument
 Plucking the rubber band while holding it at different
positions along the rubber band will produce sounds at
different frequencies. The frequencies can be visualized
using a strobe light.

Mathematical model and SA/V calculation
o Potting clay cubes – showing how a large cube will fall through water
quickly, and a small cube will take longer to fall due to drag of water –
due to SA/V increase. Also to show that the same total volume will have
an enormous SA as the original object is cut into small pieces, exposing
more atoms that had been hidden inside the object.
 Provide students with a 10cm x 10cm block of potting clay
 Measure and record the following
o Length, width, height, area of side, number of sides
 Calculate the following
o Total surface area (SA), volume (V), SA/V

Cut the clay into cubes half the size of the original length
 Repeat and measurements and calculations
 Also count the number of cubes
 Calculate and record the total V and SA of all cubes

Repeat cutting 4 times
 Be sure students understand that they do not have to cut all
cubes as this will be very time consuming.

Graph SA/V vs. length of a side (curve should be 6/X)

Fill an aquarium with water and time the fall of each object in the
water (do not change the water height, so you need to remove the
object each time, or drop objects simultaneously)