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Understanding the structure of a muscle cell

Video 1: Explores what angles are
Video 2: Provides examples of angles
Video 3: Misconceptions about angles

This video explores the angles found in parallel lines.

Introduction to bacteria

Introduction to cell theory--the idea that 1) all living things are made of one or more cells, 2) cells are the basic unit of life and 3) all cells come from other cells. Explore the roles that Hooke, Leeuwenhoek and others played in developing cell theory.

Hooke and Leeuwenhoek were two of the first scientists to use microscopes to study the microscopic world of cells. Hooke coined the term "cell" after observing the tiny compartments in cork, while Leeuwenhoek discovered a variety of living creatures in pond water, blood, and other samples. They contributed to the cell theory by suggesting that cells are the fundamental units of life and structure, and that all living things consist of one or more cells that originate from other cells by division. 

All living things are made up of cells, which is the smallest unit that can be said to be alive. An organism may consist of one single cell (unicellular) or many different numbers and types of cells (multicellular).

There are some key words that you need to know for circles: radius, circumference, diameter, sector, segment, tangent, chord and arc. In this video you will discover what they all mean.

This video discusses the topic of circles.

Plant cells have a cell wall in addition to a cell membrane, whereas animal cells have only a cell membrane. Plants use cell walls to provide structure to the plant. Plant cells contain organelles called chloroplasts, while animal cells do not. Chloroplasts allow plants to make the food they need to live using photosynthesis.

Video 1: Construction of a circle when its radius is known
Video 2: Examples of how to construct a circle
Video 3: Common mistakes made when constructing a circle