Learners view animations showing methods of measuring the pH level of a solution using litmus paper and electronic instruments.

Learners view an animated presentation showing how the pH level of a cleaning solution is controlled in a closed-loop system in a manufacturing setting. A quiz completes the activity.

In this animated object, learners view hydrogen and hydroxide ions in a solution. A brief quiz on the basic principles of the term pH completes the activity.

Learners review normal conditions that are associated with aging. Changes are highlighted in the cardiovascular, musculoskeletal, respiratory, gastrointestinal, urinary, reproductive, endocrine, nervous, and sensory systems.

This animated lesson shows how a photoelectric sensor, connected to a ladder circuit, causes the cylinder of a hydraulic circuit to extend and retract.

In this screencast, learners examine the action of insulin and other antidiabetic medications.

Learners complete sentences using the correct phrasal verb.

Learners examine phase diagrams that show the phases of solid, liquid, and gas as well as the triple point and critical point.

The learner identifies if phrasal verbs are used correctly in a sentence. If they are not used correctly, the student substitutes the correct answer.

In this animated activity, learners view the following physics concepts in action: force, friction, horsepower, work, power, inefficiency, resistance, inertia, and energy.

The learner will understand the two methods used to create a phase shift in current between two windings.

Learners view a demonstration showing that line-neutral voltages and line-line voltages are not in-phase with each other, but have a definite 30-degree relationship.

In this learning activity you'll review information on the neural synapse.

In this interactive object, learners select the correct description of a child in the five stages of development in the following categories: pattern of growth, vital signs, organ development, vision and hearing, and developmental stage.

Learners examine how melting, vaporization, and sublimation require energy input while freezing and condensation release energy.

In this interactive object, learners practice using the phrasal verbs "get on," "get over," "get away," "get down to," and "get away with."

This animated object illustrates the events leading to the migration of phagocytes into areas of tissue damage and/or bacterial presence. Learners view bacterial cell phagocytosis, its subsequent enzymatic digestion, and exocytosis.

In this interactive object, learners examine terminology dealing with phonics and whole language and identify the different types of activities that would be seen in a phonics-based or whole language classroom. Part of this activity has audio.

In this interactive object, the learner matches various disorders to the acid-base disturbances they cause.

Students read different definitions of "acids" and "bases." In an interactive exercise, they identify if a substance is an acid or a base.