The evidence for "microevolution" (adaptive changes within species) is supported by an abundance of easily observed examples. However, "macroevolution" (including speciation and the formation of all major groups of organisms by that same process repeated over millions of years), is not as obvious to many people. Nevertheless, there are several different lines of evidence that do indeed point to this very convincingly. Take the time to explore the online links mentioned to further extend your understanding, and, more importantly, help your students to explore these, too.

Chromosome Comparisons: First, there are the very striking similarities between all of our chromosomes and those of the apes. Take a look at this at http://www.indiana.edu/~ensiweb/lessons/chro.all.html. For an even sharper version (if you have wideband internet access, e.g. DSL), be sure to scroll to the bottom of that page and download the high resolution PDF file mentioned there. The result is quite suitable for printing copies for your students to study. You might even want to use one of the ENSI lessons that give students a chance to study these more closely, including clear examples of inversions, etc.: The Chromosome Connection, at http://www.indiana.edu/~ensiweb/lessons/chr.con2.html, and Comparison of Human and Chimpanzee Chromosomes, at http://www.indiana.edu/~ensiweb/lessons/chromcom.html.

Most people assume that chromosome numbers are a constant for each species and that this supposedly prevents functional fertility between species. It turns out that this is not quite true. A particularly revealing article can be found at http://www.gate.net/~rwms/EvoEvidence.html. It's only about two pages, but be sure to read it all, especially the few paragraphs beyond the chromosome diagrams, regarding chromosome variations within a species, and fertility between species. There are a number of examples where different species, with different chromosome numbers, have produced fertile offspring.

Even more impressive (in that same article, and also discussed on another site: http://www.edwardtbabinski.us/articles/chimp_chromosome.html) is the clear evidence that our chromosome #2 is a result of the end-to-end fusion of two shorter chromosomes (found today in apes: chimps, gorillas, and orangutans), probably very early in our hominid line, after chimps and gorillas branched off on their own lines from our common ancestor. The banding patterns of those chromosomes provide a strong indication of this, and subsequent DNA sequencing further confirms it. If that fusion indeed did happen, then we should be able to find evidence of chromosome ends meeting near the middle of chromosome #2. As it happens, all chromosomes have many repeats of the same DNA sequence at both ends (telomeres). Upon inspection, such "tandem repeats" are indeed found in the region of chromosome 2 exactly where they must have fused. This is very compelling, something very hard to explain either by special creation or intelligent design, but easy to explain as an event in evolution.

Our new Chromosome Fusion lesson can be used in biology classes for students to find those same DNA sequences using the same internet tools and databases that scientists use. http://www.indiana.edu/~ensiweb/lessons/c.fus.les.html.

In addition, there are the patterns of molecular evidence that make sense only if macroevolution has occurred. One of several lessons on this site is the comparison of beta hemoglobin in primates, at http://www.indiana.edu/~ensiweb/lessons/mol.prim.html. Similar studies have been done with a huge number of species and many different proteins, all with similar indications: macroevolution.

And don't overlook the abundant fossil evidence, much of it pointing clearly to macroevolution. A most revealing resource showing this is "Transitional Fossils", summarized from a much larger article on the Talk Origins site (see link to the original article in that summary), by Kathleen Hunt: http://www.indiana.edu/~ensiweb/lessons/c.bkgrnd.html.

A very recent addition (Jan. 2006) to the TalkOrigins site is "29+ Evidences for Macroevolution at http://www.talkorigins.org/faqs/comdesc. Finally, be sure to check out the long list of actual Observed Examples of Speciation, at http://www.talkorigins.org/faqs/faq-speciation.html.

Additional ENSI lessons that reflect macroevolution include the following:
Becoming Whales: http://www.indiana.edu/~ensiweb/lessons/theor.ch.html
Hominid Cranium Comparisons: http://www.indiana.edu/~ensiweb/lessons/hom.cran.html

Macroevolution & Classification Diagram: Diagram that illustrates macroevolution, and relates it to classification. Includes instructions for its use in class.