Biology is the
scientific study
of living things. Its
many branches are devoted
to different kinds of life,
including botany (the study
of plants) and zoology (the study of
animals). The most important idea in
biology is the theory of evolution by
natural selection, which explains how
living things came to exist in their
current form.Biology
SCIENCETHE SCIENCES
Since science began over 2,000 years ago, our knowledge
of the world has increased enormously. Science has led
to many discoveries that have transformed society,
such as cures for diseases. It’s also led to amazing new
inventions, such as telephones, televisions, space rockets,
and computers. These practical spin-offs of science are
called technologies.
Medicine is the
science of healing
illnesses. In the past,
people believed that
diseases were a punishment for
bad behavior. Scientists now
know that most diseases are
caused by microscopic
organisms,
inherited genes,
or faults with
a person’s
immune system.
Medicine
All substances are made
of chemicals, from your
hair and teeth to the air
around you and the
paper in this book.
Chemists investigate
how atoms join
together in different
ways to form
molecules, or how
molecules break
apart and recombine
to form new
substances.Chemistry
Geology is the
study of the Earth
and its interior.
Geologists study
how rocks form
from chemicals
called minerals
and how they break down or change
into new types of rock. Geologists also
look at processes that happen deep
underground in Earth’s interior.
These processes cause earthquakes
and volcanoes, and continually
reshape our planet’s surface
over long periods of time.Geology
Planet Earth is a tiny speck of matter
in a vast universe of planets, stars,
galaxies, and colossal areas of empty
space. Astronomy is the study of this
gigantic realm beyond our own
planet. Thanks to rocket technology,
astronomers can now study space
first hand.Astronomy
Physicists investigate energy and
movement. They study the tiniest
particles of matter that make up
atoms, and things that aren’t
made of matter at all, such as
time, light, gravity, and
space. The work of physicists
led to the discovery of
radio waves, which gave
us television and cell
phone technology.Physics
FOSSIL
Preserved remains
of living things
helped scientists
to understand
evolution.2211869 18901956 1953
Scientists developed
the atomic theory.
They knew how
atoms are put
together and how
they break apart.Internet Tim Berners-
Lee invented the World
Wide Web, a new way
of sharing information.1989
Dmitri Mendeleyev
was a Russian chemist.
He laid the foundations
of modern chemistry
when he wrote the
Periodic Table.19051915
Albert Einstein’s
theories of relativity
changed physics
with new ideas
about space, time,
light, and gravity.Francis Crick and James
Watson unraveled the
structure of DNA, the
genetic code inside
living things.