January 3, 2012
by: Tami O’Connor
Density is not typically an easy concept for most middle school students and even more difficult for younger students, but it doesn’t need to be. We all know that D=m/V, but the easiest way I found to explain it to my students was to have them visualize a common dilemma in my home immediately preceding a vacation. For years, as a poor starving teacher, I only had one suitcase, and it was actually a hand-me-down from my mother. It was a medium sized Samsonite, hard cased piece of luggage. When approaching the topic of density in my classroom, down from the attic it came.
My explanation began with an imaginary week-long summer vacation to a low-key resort. The class and I would brainstorm the items I needed to pack for my trip. Generally, the list included items such as a few bathing suits, shorts, t-shirts, a pair of flip flops, some PJs, underwear and a few toiletries. It was obvious by looking at the size of my suitcase that in addition to my meager belongings, I could have probably also fit one of my students in my bag… ok, perhaps one of the smaller kids.
I explained that when I closed the suitcase, it was hard to see, simply by looking at it, how heavy it was. The lesson didn’t stop there. We now planned my one-week ski vacation to Vermont during the February break. Once again, my students and I made up my pack list. The list included a couple of heavy sweaters, long johns, gloves, a hat, boots… as you can imagine, the list went on and on. The question was, where to put it all. Of course, since I had only one suitcase, the answer was easy. Read the rest of this entry »
December 3, 2010
by Ron Perkins
At first glance No-Pop Bubbles may seem like any other bubbles. While the bubble solution is a bit more viscous, one blows No-Pop Bubbles like any other bubble. The small bubble wand suspends a bubble film which, when air is blown through it, releases small bubbles into the air.
These bubbles, however, are no ordinary bubbles. No-Pop Bubble solution begins as a regular soap and water bubble solution. Added to this solution is a small amount of a non-toxic water soluble polymer. When No-Pop Bubbles are first blown, the bubbles behave like ordinary bubbles. As the water evaporates from the bubble’s surface, however, an extremely thin plastic ‘bubble skeleton’ remains. It is this plastic bubble skeleton which has the properties for which No-Pop Bubbles are named. Read the rest of this entry »
November 12, 2010
by: Michelle Bertke and Melanie Bunda
Bubbles are always a fun and interesting activity for kids of all ages. However, bubbles are not only fun, they are also an excellent teaching tool for some abstract concepts such as air density, dissolved gasses, and air pressure. Below is a collection of bubbly activities that highlight each of these topics. Educational Innovations offers a full line of wonderful bubble products!
Gravity Defying Bubbles
Different gasses have different densities. The air around us is mostly nitrogen (N2) and oxygen (O2), which are both lighter than carbon dioxide (CO2). When a heavy gas, such as CO2 is placed in a tank, it will sink to the bottom without mixing. This can be achieved by placing a few blocks of dry ice in a large fish tank or clear plastic bin covered loosely with a lid and allowing them to sublime. This will take several minutes. Always use caution when handling dry ice by using proper gloves and safety goggles.
Once full, blow bubbles over the surface of the tank. When the bubbles reach the interface of the two gasses, they will float. If you fill the tank with CO2 unnoticed, have the kids speculate as to why they think the bubbles didn’t reach the bottom, and what might be in the tank.
An alternative is to fill a balloon with CO2 by filling it with baking soda (or an alka seltzer tablet) and placing it over the opening of a bottle filled with vinegar (or water). Lift the balloon so the contents spill into the bottle and react with the liquid, allow the balloon to fill from the reaction, twist and remove. Use it to blow bubbles. Compare these bubbles to those blown with regular air (use a fan, not your breath for best results). Have students compare the two bubbles. Which one falls faster? Which one floats longer? Read the rest of this entry »
August 13, 2010
by: Tami O’Connor
Why do some objects float while others sink? Archimedes discovered that an object is buoyed upward with a force equal to the weight of the fluid displaced. An object will float in a fluid whenever its weight is less than the weight of the fluid displaced; otherwise it will sink… So what does this mean in English??? An easier way to think about it is that an object that is less dense than the fluid it is in will rise to the top of the more dense fluid.
In demonstrations of liquids of varying densities, the liquid with the greatest density will sink to the bottom of the container while the less dense liquid will remain on the top. There are wonderful demonstrations you can conduct with your class using immiscible liquids (liquids that do not mix) of different densities, and there are a number of high interest experiments your students can conduct using liquids of different densities. If you find this topic interesting, please visit the blog we wrote on the W-Tube.
Gasses also have varying densities, but in the elementary and middle school classrooms, students don’t often have the same opportunity to work with gasses as they would liquids, or more often, liquids and solids. Read the rest of this entry »
March 30, 2010
by: Cynthia House
I sponsor an after school Science Club in a K-5 elementary school. The club is organized into two-week-long sessions, each session focusing on a specific topic. One of this year’s most successful sessions involved the Archimedes Balance from Educational Innovations.
Archimedes Balance Experiment 1:
- answer sheet, listing the sample materials and their densities
- fill-in table to record findings:
Students worked in pairs with first and second grade children teamed with a fourth or fifth grade student. We introduced the topic with a brief Power Point biography of Archimedes and his accomplishments, focusing on the story of King Hieron’s crown. Then students practiced determining the density of materials using the Archimedes balance and the samples supplied in the sets (all directions are included in the kit).
The Archimedes Balance relies on Archimedes’ principle which states that a floating object displaces its own weight of fluid. The balance consists of a graduated cylinder partially filled with water and a tube that fits inside the cylinder and can float in the water. By placing an object inside the inner tube and measuring the amount of water displaced, you can easily determine the objects weight. Read the rest of this entry »