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Learn about DNA (deoxyribonucleic acid). Overview of DNA bases, complementary base pairing, and the structure of the double helix.

Enzymes as catalysts for reactions in biological systems; discussion of substrates, active sites, induced fit, and activation energy.

By the end of this lesson you will be able to:

1. Define and explain what a force is
2. List and describe the main kinds of forces
3. Explain the effects of a force

saac Newton (1642–1727) was a natural philosopher; a great thinker who combined science and philosophy to try to explain the workings of nature on Earth and in the universe. His laws of motion were just one part of the monumental work that has made him legendary. The development of Newton’s laws marks the transition from the Renaissance period of history to the modern era. This transition was characterized by a revolutionary change in the way people thought about the physical universe. Drawing upon earlier work by scientists Galileo Galilei and Johannes Kepler, Newton’s laws of motion allowed motion on Earth and in space to be predicted mathematically. 

Short Physics tutorial on Forces. On completion you will be able to 

1. Define and explain what a force is
2. List and describe the main kinds of forces
3. Explain the effects of a force

From the extinction of the dinosaurs to humanity.

Video 1: The meaning of percent
Video 2: Meaning of 109%
Online activity 1: Percents
Video 3: Percents from fraction models 
Online activity 2: Percents from fraction models 

Kubainisha asilimia ya kiasi na msingi

Identifying percent amount and base: Khan Academy video with the audio translated into Kiswahili. 

Kuelezea maana ya asilimia

Describing the meaning of precent: a Khan Academy video on percentages with the audio translated into Kiswahili

How variation can be introduced into a species.