NanoscienceCasey Moore7th Grade Life ScienceGunston Middle SchoolArlington, Virginia

In my classroom• Virginia SOLs for 7th grade include metric

conversions from kilo- to milli-.• My students were curious about what was

smaller than a millimeter.• They had never used microscopes, nor did

they know there were organisms smaller than a millimeter.

• Many students didn’t know what cells were.

In my classroom

My students determined that the smallest thing they had seen in class was a newly hatched brine shrimp.

They measured the brine shrimp using a transparent millimeter ruler under the microscope.

A newly hatched brine shrimp is about 1mm.

Searching for brine shrimp

Viewing the brine shrimp under 100X magnification

Students use a millimeter ruler to determine the size of the brine shrimp

Document camera helps to teach measurement in the microscope

The shrimp swims by and we can measure the length

King Henry died by drinking chocolate milk

kilo hecto deka (base) deci centi     milli

Each letter represents a decimal place when converting between prefixes.

7th grade metric conversion

“What’s smaller?”

My students wanted to know what was smaller than milli, so we wikipedia-ed it: http://en.wikipedia.org/wiki/SI_prefix

Extension:  converting between milli-, micro-, nano-

    m    .    .    u   .    .    n

Working with scale

Students know that a brine shrimp is 1mm

Convert 1 millimeter to nanometers

1mm = _____nm

m    .    .    .    .    .    n

move the decimal point 6 places to the right

1mm = 1 000 000nm

Working with scale

Students also learn how to measure the field of view of a compound microscope.

In a lab they discover that they can see .1mm in a field of view using 400X.  

This means that they are able to see 100 000nm across.

The smallest objects they see with this objective lens is microorganisms from a pond.  These microorganisms measure approximately .01mm.  

This means that my students have seen living things equal to 10 000nm

Assignment

• Goal: To give students an idea of how small a nanometer is.

• Objective: To create a scale model that represents a nanometer in comparison to unicellular organisms students observe and measure using a compound microscope.

• 1. What is the diameter of the smallest organisms you saw in the mini-pond?

.01mm

2. How many nanometers are in .01mm?

.01mm = _____________nm

.01mm = 10 000nm

3. Write a ratio that shows that a 100 meter field represents the smallest microorganism you can see with a 400X microscope (scale) in nanometers.

10 000nm : 100m

4. Write a proportion to find how much of the 100 meter field would represent one nanometer.

10 000nm = 1nm 100m X

5. Solve the proportion. How much of the 100 meter field represents one nanometer?

X = .01m

6. Convert this number to centimeters.

.01m = 1 cm

Convert this number to millimeters.

1cm = 10mm

1.How many fields would the brine shrimp cover at the same scale? (assuming a brine shrimp is 1mm) (100m=.01mm)

.01mm = 1mm100m x

x = 10 000 meters = 100 fields!

Websites that show scale

Utah Genetics

Cells Alive Brainpop!(keyword nanoscience)