4–8 Grade:

1. Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.
2. Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.3. Extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient to allow its survival.
3. Fossils indicate that many organisms that lived long ago are extinct. Extinction of species is common; most of the species that have lived on the earth no longer exist.

9–12 Grade:

1. Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuing selection by the environment of those offspring better able to survive and leave offspring. [See Unifying Concepts and Processes]
2. The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.
3. Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.
4. The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.
5. Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.

4–8 Grade:

1. Geologic time can be estimated by observing rock sequences and using fossils to correlate the sequences at various locations. Current methods include using the known decay rates of radioactive isotopes present in rocks to measure the time since the rock was formed.

9–12 Grade:

1. The earth processes we see today, including erosion, movement of lithospheric plates, and changes in atmospheric composition, are similar to those that occurred in the past. earth history is also influenced by occasional catastrophes, such as the impact of an asteroid or comet.
2. Fossils provide important evidence of how life and environmental conditions have changed.

Geologic History; Correlate rock units with general geological time periods in the history of the earth; evaluate and interpret geologic history using geological maps; interpret topographic maps to identify and describe significant geological history/structures in PA; Describe the processes that formed PA geologic structures and resources including mountains, glacial, water gaps, and ridges; examine and describe recurring patterns that form the basis of ...geological order: Explain the mechanisms of the theory of evolution;

Interpret Geological Evidence Supporting Evolution; Analyze how models, systems...changed over time (evolution); Critically evaluate the status of existing theories (evolution); Analyze and evaluate earth features and processes that change the earth - Interpret geological evidence supporting evolution;