This description of the fossil record of bacteria focuses on one particular group of bacteria, the cyanobacteria or blue-green algae, which have left a fossil record that extends far back into the Precambrian. The oldest cyanobacteria-like fossils known are nearly 3.5 billion years old and are among the oldest fossils currently known. Cyanobacteria are larger than most bacteria and may secrete a thick ... Full description.

Information on this page pertains to dinoflagellates, the fossil record of which may extend into the Precambrian. Spherical organic-walled microfossils known as acritarchs, some of which may be dinoflagellate hystrichospheres, first appear in rocks about 1.8 billion years old. Exactly what the acritarchs were is not known with certainty; they probably included a number of clades of eukaryotic algae, ... Full description.

This bioluminescence activity will help students to understand how animals produce and use light in the deep ocean. Students will describe, compare, and contrast bioluminescence, fluorescence, phosphorescence, and chemiluminescence. They will explain the role of three major components of bioluminescent systems and will explain how three organisms use bioluminescence. In addition, students will discuss ... Full description.

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 9-12. This lesson covers the exploration of Mars from the 1960s to recent times. Information includes mission findings, and the NASA 3 phase strategy of finding information (reconnaissance, surveillance, in-depth study). It includes objectives, materials, procedures, discussion questions, evaluation ideas, suggested ... Full description.

This classroom module consists of a series of activities that prepare students to give a presentation about the Earth system. Topics covered include the definition of a system, examples of systems, and the Earth system. The teacher's page includes assessment tools such as concept mapping and an evaluation rubric. Full description.

About three billion years ago, single-celled underwater bacteria similar to modern cyanobacteria consumed carbon dioxide as they photosynthesized, releasing oxygen in the process. In this way, an atmosphere full of volcanic carbon dioxide gradually changed into an oxygen-rich atmosphere in which animal life could survive, except for some primitive organisms, who retreated to oxygen-poor environments. ... Full description.

These science activities are meant to spark student curiosity and engage students in various science process skills, as well as present them with science content. They involve concepts related to static electricity, air pressure, density, energy transfer, the Bernoulli Principle, adhesion and cohesion. Full description.

PALS is an on-line, standards-based, continually updated resource bank of science performance assessment tasks indexed via the National Science Education Standards (NSES) and various other standards frameworks. The tasks, collected from numerous sources, include student directions and response forms, administration procedures, scoring rubrics, examples of student work, and technical quality data calculated ... Full description.