Displaying 1 - 10 of 11 Resources

Cell theory

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. 

Subject and Topic
Form 1
Biology
Cell structure and organisation
Concept of cells
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2015
Creator/Author
Sal Khan
Keyword
Cells

Cells and organisms

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).

Subject and Topic
Form 1
Biology
Cell structure and organisation
Concept of cells
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2022
Creator/Author
Khan Academy
Keyword
Cells

Effects of different wavelengths of radiation

When electromagnetic radiation is absorbed by a material the energy it carries has to go somewhere. When lower energy waves, like radio and infrared waves, are absorbed there can be an increase in temperature of the absorbing material. Higher energy waves, like x-ray and gamma waves, can actually permanently damage or change materials. Learn about the different types of electromagnetic waves and how their energies can influence their effects on objects.

Subject and Topic
Form 1
Physics
Waves
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2021
Creator/Author
Sal Khan
Keyword
Electromagnetic Radiation
Wavelength
electromagnetic waves

Fractional Exponents to Radicals

Use the dynamic worksheet to practice simplifying expressions with fractional exponents, rewriting them as radicals.

Subject and Topic
Form 2
Mathematics
Exponents and radicals
Radicals
Resource Type
Werkbladen en klassikale activiteiten
Language
English
Publisher
GeoGebra
Publication Date
2019
Creator/Author
Audrey McLaren
Steve Phelps
Keyword
Exponents
Fractional Exponents
Radicals

Introduction to the cell

Introduction to the cell.

Subject and Topic
Form 1
Biology
Cell structure and organisation
Concept of cells
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2017
Creator/Author
Sal Khan
Keyword
Cells

Radicals and Rational Exponents

In this section, you will:

  • Evaluate square roots.
  • Use the product rule to simplify square roots.
  • Use the quotient rule to simplify square roots.
  • Add and subtract square roots.
  • Rationalize denominators.
  • Use rational roots.
Subject and Topic
Form 2
Mathematics
Exponents and radicals
Radicals
Resource Type
Cursus
Language
English
Publisher
openstax
Publication Date
2017
Creator/Author
Jay Abramson
Keyword
Exponents
Radicals
Rational Exponents

Scale of cells

Even though molecules, proteins, viruses, and cells are all tiny, there are significant size differences between them. The diameter of a water molecule is roughly 0.28 nanometers. The diameter of the protein hemoglobin is roughly 5 nanometers. The diameter of the HIV virus is roughly 120 nanometers. A red blood cell is 6-8 micrometers.

Subject and Topic
Form 1
Biology
Cell structure and organisation
Concept of cells
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2015
Creator/Author
Sal Khan
Keyword
Cells

Simplifying Radicals

Exercises requiring expressions to be re-written in 'Simple Radical Form'.

Subject and Topic
Form 2
Mathematics
Exponents and radicals
Radicals
Resource Type
Werkbladen en klassikale activiteiten
Language
English
Publisher
GeoGebra
Publication Date
2020
Creator/Author
Courtenay Fullerton
Tim Brzezinski
Keyword
Exponents
Radicals

Wave interference

An explanation of wave interference and solution of a few examples to find the value of the total wave when two wave pulses overlap

Subject and Topic
Form 1
Physics
Waves
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2016
Creator/Author
David SantoPietro
Keyword
Waves
Wavelength
Wave Interference
Mechanical Waves
Mechanical Sounds

Wave Properties

The wavelength and frequency of a wave are related to one another by the speed of travel of the wave, which depends on the type of wave and the medium through which it is passing.

Subject and Topic
Form 1
Physics
Waves
Resource Type
Video
Language
English
Publisher
Khan Academy
Publication Date
2021
Creator/Author
Khan Academy
Keyword
Waves
Wavelength