Video Demo: Reaction Chamber

This is a demo that I only show the video. This is an example of what happens in the reaction chamber of a liquid fuel rocket. I use about 100 ml of denatured alcohol. I pour it into the 5 gallon plastic bottle. I swirl it around vigorously, trying to speed up the evaporation of the alcohol. I pour out the excess liquid alcohol. I then set the bottle on the counter, making sure it is flat. With a candle attached to the end of the meter stick, I insert the candle in the opening of the bottle. Again, I only show the video of this to my students and don’t do it live. It demonstrates the volatile reaction that occurs with oxygen in the air. The resultant hot gasses funnel through the opening (nozzle on a rocket) at a higher speed. This demo also shows when the particles of a chemical are spread out (increased surface area), the speed of a reaction increases.

ONLY TEACHER DEMO! I ONLY RECOMMEND TO TEACHERS THAT THEY ONLY SHOW THIS VIDEO IN CLASS AND DON’T DO THE DEMO IN CLASS. NEVER, EVER USE A GLASS BOTTLE! ONLY USE A PLASTIC BOTTLE.

Video Demo: Water Up

An inverted 100 ml beaker is placed inside a 400 ml beaker filled with colored water. The 400 ml beaker is placed on a hot plate. The water boils for a while, and then the beaker is removed. The water vapor inside cools condenses back into liquid. The molecules of a liquid take up less space than a gas, and therefore the pressure inside lowers. The atmospheric pressure pushes the colored water up inside the beaker. This demonstration can be found in Tik L. Liem’s Invitations to Science Inquiry.

Genetic Engineering in the Classroom

Genetic engineering may be the single most important development in biology in the last 20 years. Bio Rad is a terrific Bay Area company that sells easy to use kits that can be used in the classroom. Bio Rad’s pGLO transformation kit (see below) essentially allows students to insert the Green Fluorescence Protein (GFP) from a jellyfish and insert it into E. coli bacteria. With this inserted gene the bacteria make GFP and thus the bacteria glow green under UV light. The name of the kit is the pGLO Bacterial Transformation Kit. For detailed explanation of the kit, see video below.

pGLO kit

kit contents

video demonstration of kit

Science of 4th of July

The fourth of July means fireworks.  Here is a list of 10 science facts about fireworks, including the health affects of the smoke.  Here is also a good simple explanatory video of how a firework works.

Here is video on a red, white, and blue Mentos and Diet 7up reaction and explosive watermelon carving, via Steve Spangler.

Lesson: Google Maps/Earth Solar System Scale Model

Google Maps has recently developed “My Maps” where Google Maps can be annotated with pictures, lines, shapes, and points. I incorporated this new tool with one of my all time favorite lessons: The Solar System Scale Model. This model shows the Sun and the nine planets (yes I still include Pluto for comparison reasons) to scale in both size and distance. For details download the student (word document) and teacher handout (word document). You can take a look at the model in action by going to Google Maps or download the Google Earth kml file to look at in Google Earth. Below is a short narrated video clip of the Google Earth version.