In this animated and interactive object, learners study how a DC circuit, consisting of a diac, a capacitor, and two resistors, causes a light-emitting diode to turn on and off. A brief quiz completes the activity.

Students read about light-emitting diodes, including LED voltage and current, and how to protect against reverse voltage.

Learners test their ability to visualize an angled mount in this interactive exercise that features animated pictorial views.

In this animated activity, learners examine the operation of the SCR, including how it is biased and how it is turned off. A brief quiz completes the object.

This animated lesson shows how a pressure switch connected in a ladder circuit causes the cylinder of a hydraulic circuit to extend and retract.

In this interactive object, students read how to calculate the blank size for cylinders in a three-roll pinch roller. A calculator is required for the brief quiz that completes the activity.

Learners test their spelling ability by identifying misspelled words from lists of words commonly used in business.

Learners match diseases with their portals of entry, causative agents, and associated vectors.