In this learning activity you'll locate the countries of Central America on a map.

Learners review the names of the capital cities of the seven Central American countries and locate the cities on a map.

Students read about the countries of West and Central Africa and identify them on a map.

Learners take a virtual tour of the wide web central impression press and read directions for the operation of each component. This object includes animation, video clips, and audio.

In this learning activity you'll apply techniques for identifying a central idea to a practice exercise.

Learners read the definitions of various water forms and locate the bodies of water on a map.

Learners read the definitions of geological terms and identify the landforms in various images.

This interactive activity represents the grid modeling technique, a heuristic model for choosing a centralized location for a manufacturing or distribution center within a supply chain network. The formula calculates a central point between the suppliers and the markets. This object requires the latest version of Flash Player.

In this animated and interactive object, learners observe how two, three, or four groups of electrons around the central atom cause the shape of the molecule to be linear, trigonal planar, bent, tetrahedral, or pyramidal. Seven examples and eight interactive questions are provided.

In this interactive and animated object, students distribute the valence electrons in simple covalent molecules with one central atom. Six rules are followed to show the bonding and nonbonding electrons in Lewis dot structures. The process is well illustrated with eight worked examples and two interactive practice problems.

Learners examine how five or six groups of electrons around a central atom cause the shape of the molecule to be trigonal bipyramidal, seesaw, T-shaped, linear, octahedral, square pyramidal, or square planar. Seven examples and three interactive questions are provided in this animated activity.

Walk through the subscriber loop and learn how the signal travels from the central office to the subscriber.