Photographing Science
by: Martin Sagendorf
It’s Easy:
To take neat photos of little things.
We Think: Read the rest of this entry »
Picture This!
January 10, 2013
Leave a Comment » | 
College level, High School level, Physics | Tagged: digital camera, iPhone pictures, magnification, photography, spectroscope | 
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Posted by Tami O'Connor
Growing Spheres Help Students Absorb Scientific Principles
March 14, 2012
by: John Fedors
Hydrophilic spheres from Educational Innovations offer a variety of interesting applications and opportunities for scientific inquiry. They come in a variety of sizes: regular, jumbo, & gigantic. For the following examples, I prefer the regular or #710 size. However, whichever size you choose, they will expand to about 300 times their original dehydrated size.
As they absorb the water, they become almost invisible, due to having the same refractive index as water. When placed in de-mineralized or distilled water and kept away from sunlight, they will dehydrate to their original size and can be re-used. Dehydration time will depend on air humidity.
Once enlarged, these clear spheres can be used to demonstrate:
* The lens of an eye (such as those of a shark, calf or sheep) that has the ability to magnify the print on a page. A thin slice may be used to mimic a cornea transplant.
* The suspension of small items such as a coin.
* Roots of a germinating seed.
Enlarged growing spheres can also help to observe the relationship of Surface Area (A=4pr2) to Volume (V=4/3pr3) mass in grams. They can be used to graph relationships. Read the rest of this entry »
Leave a Comment » | Biology, Chemistry, College level, Elementary level, experiments, High School level, Middle School level | Tagged: dialysis tubing, hydrophilic, jelly spheres, organelles, osmosis, PBL, phenomenon based learning, phenomenon-based science, science, serpent skin tubing | Permalink
Posted by Tami O'Connor
Coupled Pendulums with Video
December 2, 2011by: Martin Sagendorf
One Pendulum…
Is interesting, but…
Two Pendulums…
Are much more interesting.
But only if they are coupled pendulums.
4 Comments | College level, energy, experiments, High School level, Middle School level, Physics | Tagged: coupled pendulums, energy, harmonic motion, momentum, pendulums, Physics, resonance | Permalink
Posted by Tami O'Connor
Make Your Own Clock Faces
October 10, 2011by: Martin Sagendorf
A Definition:
Clocks measure time – it can be a continuous measure of events passing or the measure of the interval between two events.
Of Hours:
After years of evolution, our modern clocks now divide the day into 24 equal length hours. And, as we know, there are two systems in use today: Americans use the “double-twelve” system while the rest of the world uses the 24 hour system.
As An Aside:
The word “hour’ comes from the Latin and Greek words meaning season, or time of day. A “minute” from the medieval Latin pars minuta prima (first minute or small part), originally described the one-sixtieth of a unit in the Babylonian system of sexagesimal fractions. And “second” from partes minutae secundae, was a further subdivision on the base of sixty – i.e. “a second minute”. (ref. Pg. 42 The Discoverers by Daniel J. Boorstin)
The “Double-Twelve” Clock Face:
Has 12 at the top – probably because at noon the sun is at its highest point in the sky.
But…
We can make a clock with 12 o’clock anywhere we wish and the clock will still work just fine. Read the rest of this entry »
2 Comments | Chemistry, College level, Elementary level, High School level, Middle School level, Physics | Tagged: clock making, homeschool, interesting clock, parent friendly | Permalink
Posted by Tami O'Connor
The Law of Dulong and Petit
September 3, 2011
by: Dr. Jean Oostens
Atoms were proposed in antiquity without any experimental evidence by Democritus, a Philosopher. This must have been a problem for Newton and Leibnitz who posited that there was always a mean of considering smaller and smaller intervals of space to calculate the “instantaneous velocity”.
The introduction of the precision balance in chemistry by Lavoisier paved the way for Dalton to formulate his laws on the “definite and multiple proportions” governing chemical reactions. This supported the atomic theory, without giving it general acceptance.
Specific heat was defined as the quantity of heat needed to increase one gram of a substance by one degree. There was no definite pattern when specific heats of various substances were compared. Until two French scientists in 1819 calculated specific heat by atomic mass, forming the Law of Dulong and Petit. There appeared a number of cases where the results were quite similar: about 6 calorie per mole. This was equivalent to stating that any atom is as good as any other to store heat! This was a small step towards acceptance of the existence of atoms. An explanation for this, and the reason for the exceptions, had to wait the early 20th century explanation by Albert Einstein. By that time, atoms had gained wide acceptance from the work of Rutherford, and soon by Bohr.
Lesson on the Law of Dulong and Petit:
You are given several chunks of metal, each containing 0.6 * 1024 atoms (i.e. one mole) of one element. How will each of those samples, when dropped in a standard quantity of hot water (typically 200 mL and 70 C) affect the temperature?
Step 1. Use a good balance (at least 0.1 gm resolution) to determine which element you are dealing with. If possible confirm your identification with an additional cue. Read the rest of this entry »
1 Comment | Chemistry, College level, experiments, High School level, Physics | Tagged: Chemistry, Dulong and Petit Law, metals, mole, specific heat | Permalink
Posted by Tami O'Connor