I found a terrific website called the Periodic Table of Videos. Created by the University of Nottingham (yes that fabled town) chemists, the site has videos on 94 of the elements found in the periodic table. They try to demonstrate some of the properties characteristic of each element. Each video is on Youtube, which is unfortunate because many school districts block the site. Nevertheless it is an invaluable tool in teaching the matter and the periodic table to middle schoolers. Some of my favorite videos include:
DNA extraction in the life science classroom usually involves isolating DNA from onions, strawberries, wheat germ, sweetbreads, etc. That tends to be kind of boring. More interesting to teachers and students is isolating DNA in humans. There are kits out there (like from BioRad) that you can buy for human DNA extraction, but they tend to be on the more expensive side, and thus aren’t practical for the classroom. I just came across a cheap method for human DNA extraction. The method comes from NOVA Science Now and it seems to involve cheap everyday chemicals. I haven’t tried it yet, but I’m definitely going to check it out. For printed version click here, for animation version click here.
I just downloaded, installed and played with Molecular Workbench. It is simulation and modeling software that students and teachers can use to understand what happens in various chemical phenomena. I could see using this on the computer and showing it on the LCD projector to students. At the middle school level you can use to to show phase changes, diffusion, atomic structure, chemical bonds and chemical reactions. Below are 4 demonstrations that I have recorded using Jing.
The Bad Astronomer, Phil Plait, is one of my favorite science bloggers. He mixes skepticism, science and humor into his work. He has produced 3 high quality short videos for Hulu.com. California 8th grade science standards include the universe and the solar system and these 3 videos are a good supplement. There are short commercials before the main content of the videos.
The first is about the changing landscape of Mars using videos and images from current Mars probes.
Protein synthesis is the process that the cell goes through to make a protein from the information stored in the DNA. The video below shows a demonstration that you can do in your classroom to show how protein synthesis works. This demonstration emphasizes the following points:
1. DNA contains the information to make a specific protein.
2. The DNA is in the nucleus of the cell.
3. The DNA cannot leave the nucleus.
4. The ribosomes make the protein from the information.
5. The ribosomes are in the cytoplasm and cannot go into the nucleus.
The metaphor that I use in class is that the DNA is like a series of recipe books in the library. These books cannot be checked out/taken out of the library. The only way to get the information that is in the books out of the library is to make a copy. mRNA is the copy of the information that can leave the nucleus and go into the cytoplasm so that the ribosome can read and make the protein. Watch the video to see how it comes all together.
Teaching tips: Place the amino acids around the classroom (cytoplasm). Assign students to be specific tRNA’s. They will get the specific amino acid and bring it to the ribosome for you.
This is an activity where students examine the evolutionary relationships between 5 primates: human, chimpanzee, orangutan, gorilla, and gibbon. To determine the relationships students examine the DNA sequence of a single gene found in all 5 species. The DNA strips aren’t the real sequences, but they are based on real DNA match percentages. Students determine the percent base pair matches between each primate and human. They then construct a cladogram (a type of phylogentic tree) to show the the evolutionary relationships among the 5 primates. Watch the slide show on how to do the activity and download the student handout and DNA strips.
Let’s Grub on Some Grass Beetles is a natural selection simulation. Natural selection is the “process by which favorable heritable traits become more common in successive generations of a population of reproducing organisms, and unfavorable heritable traits become less common.” In this activity, part 1 involves variations in silver beak loon beak types. There are tweezers, spoon, and knife shaped beaks. The beak best adapted to capturing grass beetles will survive and more chances to reproduce. The tweezers and spoon beaks are best adapted. The population of silver beak loons will change to a majority of tweezers and spoon beaks. Part 2 deals with variations in grass beetle color. The green grass beetles are best adapted to hiding in the grass than the orange or yellow grass beetles. In successive generations the populations of grass beetles will shift to green colors, since they will have the best chance to survive, reproduce and pass the variation to their offspring.
A student of mine gave me an interesting Valentine present. Basically it is a simple chemical reaction in a bag. Watch the video to see how it works. You can buy these a Dollar Tree stores during the holiday season. It was exciting to see how a simple “toy” can be used to teach science!
I’m using a wonderful tool called Voicethread to demonstrate how to extract DNA from raw wheat germ. Click play on how to do the demo and to see how Voicethread can be used. Download the handout for more details.
