https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemistry-of-the-environment/x8bc8fb44369617ed:water/v/water-pollution-causes-and-types-of-pollutant 2026-04-29T07:20:45.495372596Z Water Pollution Causes and Types of Pollutant Water Pollution Causes and Types of Pollutant Khan Academy Pakistan video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Water Pollution Causes and Types of Pollutant Water Pollution Causes and Types of Pollutant https://cdn.kastatic.org/ka-youtube-converted/ID6NtYNhyfQ.mp4/ID6NtYNhyfQ.mp4 485 Water https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:aquatic-and-terrestrial-pollution/x0b0e430a38ebd23f:sources-of-pollution/v/human-impact-on-aquatic-environments 2024-06-21T23:15:14.703721694Z Human impact on aquatic environments Human activities cause significant stress to aquatic environments, leading to devastating effects on ecosystems. Warming ocean temperatures damage coral reefs, oil spills harm marine life, and nutrient pollution creates oceanic dead zones. Additionally, the introduction of toxic substances like mercury further threatens aquatic biodiversity. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/238f89e4-6b9a-4b3e-aeb5-1ae104cdfb17_1280_720_base.png Human impact on aquatic environments Human activities cause significant stress to aquatic environments, leading to devastating effects on ecosystems. Warming ocean temperatures damage coral reefs, oil spills harm marine life, and nutrient pollution creates oceanic dead zones. Additionally, the introduction of toxic substances like mercury further threatens aquatic biodiversity. https://cdn.kastatic.org/ka-youtube-converted/nZjMRq9tev8.mp4/nZjMRq9tev8.mp4 282 Water https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemistry-of-the-environment/x8bc8fb44369617ed:water/e/pollution-and-conservation-of-water 2024-06-16T13:03:12.23291439Z Pollution and conservation of water Let's solve some questions! vibhor exercise https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:aquatic-and-terrestrial-pollution/x0b0e430a38ebd23f:waste-disposal-reduction-and-treatment/v/ap-es-sewage-treatment 2024-06-21T23:15:14.703721694Z Sewage treatment The process of waste disposal, reduction, and treatment involves primary, secondary, and sometimes tertiary treatments. Primary treatment physically removes large objects, while secondary treatment uses aerobic bacteria to break down organic waste. Tertiary treatment, though not always used due to cost, targets specific wastewater components for removal. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/09af1cda-eb97-461f-8326-3c1946c6a972_1280_720_base.png Sewage treatment The process of waste disposal, reduction, and treatment involves primary, secondary, and sometimes tertiary treatments. Primary treatment physically removes large objects, while secondary treatment uses aerobic bacteria to break down organic waste. Tertiary treatment, though not always used due to cost, targets specific wastewater components for removal. https://cdn.kastatic.org/ka-youtube-converted/_a8Mbkt_o80.mp4/_a8Mbkt_o80.mp4 293 Water https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemistry-of-the-environment/x8bc8fb44369617ed:water/v/watch-cleaning-water-pollution-in-the-industrial-revolution 2023-02-23T03:52:21.566261146Z WATCH: Cleaning Water Pollution in the Industrial Revolution You might take it for granted today, but clean water was a fantasy for most people during the Industrial Revolution. Everything from sewage to dead bodies polluted Britain’s water. In this short video, Peter Griffin explains how steam engines helped filter foreign bodies from our drinking water. Like what you see? This video is part of a comprehensive social studies curriculum from OER Project, a family of free, online social studies courses. OER Project aims to empower teachers by offering free and fully supported social studies courses for middle- and high-school students. Your account is the key to accessing our standards-aligned courses that are designed with built-in supports like leveled readings, audio recordings of texts, video transcripts, and more. Register today at oerproject.com! Website: https://www.oerproject.com/World-History Facebook: https://www.facebook.com/OERProject Twitter: https://twitter.com/oerproject World History Project video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw WATCH: Cleaning Water Pollution in the Industrial Revolution You might take it for granted today, but clean water was a fantasy for most people during the Industrial Revolution. Everything from sewage to dead bodies polluted Britain’s water. In this short video, Peter Griffin explains how steam engines helped filter foreign bodies from our drinking water. Like what you see? This video is part of a comprehensive social studies curriculum from OER Project, a family of free, online social studies courses. OER Project aims to empower teachers by offering free and fully supported social studies courses for middle- and high-school students. Your account is the key to accessing our standards-aligned courses that are designed with built-in supports like leveled readings, audio recordings of texts, video transcripts, and more. Register today at oerproject.com! Website: https://www.oerproject.com/World-History Facebook: https://www.facebook.com/OERProject Twitter: https://twitter.com/oerproject https://cdn.kastatic.org/ka-youtube-converted/UdKs7_rILFg.mp4/UdKs7_rILFg.mp4 244 Water https://www.khanacademy.org/science/ap-biology/chemistry-of-life/structure-of-water-and-hydrogen-bonding/v/importance-of-water-for-life 2025-08-23T06:00:52.132252272Z Importance of water for life Discussion of the properties of water that make it essential to life as we know it: polarity, "universal" solvent, high heat capacity, high heat of vaporization, cohesion, adhesion and lower density when frozen. video https://cdn.kastatic.org/googleusercontent/2FOaIjyqdCGbemYQMl19OchAdpjXARhI8BHGjRx-pyeNtANhkuzfNfJzXm2su9ghyGh66qPbZS2wFUx3A7MFS2yH Importance of water for life Discussion of the properties of water that make it essential to life as we know it: polarity, "universal" solvent, high heat capacity, high heat of vaporization, cohesion, adhesion and lower density when frozen. https://cdn.kastatic.org/ka-youtube-converted/fxlMABxU7zU.mp4/fxlMABxU7zU.mp4 532 Water https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:aquatic-and-terrestrial-pollution/x0b0e430a38ebd23f:sources-of-pollution/e/sources-of-pollution 2026-04-29T07:20:45.495372596Z Sources of pollution Apply your understanding of sources of pollution in this set of free practice questions aligned to AP standards. exercise https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/eutrophication-and-dead-zones 2025-08-08T21:39:42.49220884Z Eutrophication and dead zones Eutrophication, derived from the Greek for "well-nourished" refers to over-nourishment of aquatic ecosystems due to excessive use of fertilizers and detergents. This leads to algal blooms, which, when they die and decompose, consume oxygen in the water, creating hypoxic or "dead" zones. This imbalance in nutrients can have devastating effects on aquatic life. Sal Khan video https://cdn.kastatic.org/googleusercontent/7fe41E4X4zGaGoFztcn8w2eP1_uLjJmKqrbt4XusfIWuOVUx8mqnQekcSauRSoKdhvIjNWD9k0eXuXjDdIrR3rVrqQ Eutrophication and dead zones Eutrophication, derived from the Greek for "well-nourished" refers to over-nourishment of aquatic ecosystems due to excessive use of fertilizers and detergents. This leads to algal blooms, which, when they die and decompose, consume oxygen in the water, creating hypoxic or "dead" zones. This imbalance in nutrients can have devastating effects on aquatic life. https://cdn.kastatic.org/ka-youtube-converted/AxaWXWd2pw4.mp4/AxaWXWd2pw4.mp4 396 Water https://www.khanacademy.org/science/ap-biology/chemistry-of-life/structure-of-water-and-hydrogen-bonding/a/hs-water-and-life-review 2025-08-23T06:00:52.132252272Z Lesson summary: Water and life Review key terms and the unique properties of water. article https://www.khanacademy.org/science/biology/intro-to-biology/science-of-biology/v/the-scientific-method 2023-09-24T07:18:20.902045194Z The scientific method The scientific method is a logical approach to understanding the world. It starts with an observation, followed by a question. A testable explanation or hypothesis is then created. An experiment is designed to test the hypothesis, and based on the results, the hypothesis is refined. This process is repeated, leading to a deeper understanding of the observed phenomenon. This method ensures our knowledge is built on a solid foundation. Sal Khan video https://cdn.kastatic.org/googleusercontent/ZNIs_jJJ4FC9r76opQp-voduNhewR1yg7uVXDBEM_Y24hZBA8y49h1pO5UogWhkhcIZ8d3xL2ZkdCfOHgPdPtws The scientific method The scientific method is a logical approach to understanding the world. It starts with an observation, followed by a question. A testable explanation or hypothesis is then created. An experiment is designed to test the hypothesis, and based on the results, the hypothesis is refined. This process is repeated, leading to a deeper understanding of the observed phenomenon. This method ensures our knowledge is built on a solid foundation. https://cdn.kastatic.org/ka-youtube-converted/N6IAzlugWw0.mp4/N6IAzlugWw0.mp4 709 Water https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemistry-of-the-environment/x8bc8fb44369617ed:water/e/melting-and-boiling-point 2023-10-18T06:56:23.146802419Z Melting and Boiling point Let's solve some questions on melting and boiling point Vibhor Pandey exercise https://www.khanacademy.org/science/chemistry/states-of-matter-and-intermolecular-forces/mixtures-and-solutions/v/boiling-point-elevation-and-freezing-point-supression 2021-01-04T18:35:20Z Boiling point elevation and freezing point depression Boiling point elevation is the raising of a solvent's boiling point due to the addition of a solute. Similarly, freezing point depression is the lowering of a solvent's freezing point due to the addition of a solute. In fact, as the boiling point of a solvent increases, its freezing point decreases. An example of this would be the addition of salt to an icy sidewalk. The solute (salt) reduces the freezing point of the ice, which allows the ice to melt at a lower temperature.​ Sal Khan video https://cdn.kastatic.org/googleusercontent/YdwpdhsXSPdhsU9N1Yymvs_Q-j829eVxo5oLdW5mWbUyJygHGvckLZTLhHymxYl9y5eTeLHYy20cIQr2NLs8TXJ_ Boiling point elevation and freezing point depression Boiling point elevation is the raising of a solvent's boiling point due to the addition of a solute. Similarly, freezing point depression is the lowering of a solvent's freezing point due to the addition of a solute. In fact, as the boiling point of a solvent increases, its freezing point decreases. An example of this would be the addition of salt to an icy sidewalk. The solute (salt) reduces the freezing point of the ice, which allows the ice to melt at a lower temperature.​ https://cdn.kastatic.org/ka-youtube-converted/z9LxdqYntlU.mp4/z9LxdqYntlU.mp4 840 Water https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:aquatic-and-terrestrial-pollution/x0b0e430a38ebd23f:types-of-aquatic-and-terrestrial-pollution/e/types-of-aquatic-and-terrestrial-pollution 2025-02-28T18:25:12.335102467Z Types of aquatic and terrestrial pollution Apply your understanding of types of aquatic and terrestrial pollution in this set of free practice questions aligned to AP standards. exercise