Video Demo: Fish Tank Spectrum

 
When studying light, students need to learn that visible light can be refracted into its different wavelengths.  Of course it's ROYGBIV (red, orange, yellow, green, blue, indigo, and violet).  A simple prism is usually used to do this, but I think there is a better way.  Fill up a fish tank with water, put it in the sun, use a mirror and ta da a spectrum!  Check out the video.

Video Demo: Refracting Jelly Marbles

From the Science Outlet, I ordered some Jelly Marbles. I tried them out this past week, and I have to say they are pretty amazing.  Check out the video of what they are and how they can be used in the classroom.  You can also learn more on how to teach refraction, by viewing the laser lens eye demo that I did a couple of months ago.

Video Demo: Conservation of Mass

How the heck do you teach the conservation of mass to 8th grade students?  Lab activities are always good, but what lab activity can be done without the students getting super confused?  Two components are required. First, a chemical reaction is needed.  It must use simple chemicals, and it should be obvious that a chemical reaction took place.  Second, it must be easily quantifiable. In other words the mass is easy to measure and it must show very clearly that mass was not lost during the chemical reaction.  I think I may have finally developed a lab activity that addresses both components.  Watch the video and download the student worksheet for more details.

Lesson: M & M Radiometric Dating

Evolution is the change in a species over time. Scientists look at multiple sources for evidence that a species has evolved overtime.  Fossils are one of those sources.  How do scientists no the age of a fossil? They use a technique called radiometric dating to determine the absolute age of a fossil.  You can use M & M"s to simulate how radioactive decay actually works.  Watch the video to see how and download the student handout (word document).

Video Demo: Diffusion Across a Selectively Permeable Membrane

This is an updated version of a past demo.  Cell membranes are selectively permeable.  That is the membrane allows some materials to pass through and not others.  This allows the cell to maintain homeostasis, a condition in which the cell maintains the proper levels of needed materials.  In this demo the plastic of the bag acts as a selectively permeable membrane.  Iodine is small enough to pass through the plastic, while the larger water molecules are too big.  Watch the video on how to do it and to see what happens.