How to Actually Use the Amoeba Sisters Water Properties Worksheet Without Losing Your Mind
The Amoeba Sisters video on the properties of water is one of the more useful short clips floating around high school biology classrooms. It runs about twelve minutes, hits the major concepts without going too deep, and has a worksheet attached to it that teachers assign almost everywhere. The worksheet itself is straightforward, but students routinely get tripped up on a few specific questions, so knowing what the answers actually are and why they matter can save you a lot of time looking for them online. The worksheet covers cohesion, adhesion, surface tension, capillary action, high specific heat, ice being less dense than liquid water, and water acting as a universal solvent. Here is how each question lands. Question 1: What is cohesion?
Cohesion is the attraction between molecules of the same substance. In water, hydrogen bonds pull individual H2O molecules toward each other. The Amoeba Sisters illustrate this with water droplets beading up on a leaf. The correct answer on the worksheet is that cohesion causes water to stick to itself. Question 2: What is adhesion? Adhesion is the attraction between molecules of different substances. Water sticking to the walls of a glass tube or to plant cell walls is the classic example. The worksheet answer is that adhesion causes water to stick to other materials.
Question 3: How do cohesion and adhesion relate to capillary action? This is where students usually mess up. Capillary action requires both properties. Adhesion pulls water up the sides of a narrow tube. Cohesion pulls the rest of the water column along with it. The worksheet answer should mention both forces working together to move water against gravity through small spaces, such as xylem in plants. Question 4: What is surface tension?
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Surface tension is the result of cohesion at the surface of a liquid. Molecules at the surface have no neighbors above them, so they pull inward more strongly, creating a kind of elastic skin. The video shows insects walking on water. The worksheet answer identifies surface tension as cohesion at the surface allowing small objects to float. Question 5: Why does ice float? Water expands when it freezes. The hydrogen bonds lock into a crystalline lattice that spaces the molecules farther apart than in liquid water. This makes ice less dense. The worksheet answer should state that ice is less dense than liquid water because of its expanded molecular structure.
Question 6: What does high specific heat mean? Water can absorb a lot of heat before its temperature rises significantly. This is because energy is first used to break hydrogen bonds rather than increase molecular motion. The worksheet answer should reference water's ability to resist temperature changes and help organisms maintain stable internal temperatures. Question 7: Why is water called the universal solvent?
Water dissolves more substances than any other liquid because of its polarity. The partially positive hydrogen ends and partially negative oxygen end attract a wide range of ions and polar molecules. The worksheet answer is that water's polarity allows it to dissolve many different substances. I spent a lot of time going through this worksheet with students who kept mixing up cohesion and adhesion. The easiest fix I found was to stop trying to get them to memorize definitions and instead have them trace the path of water through a plant from roots to leaves, labeling where adhesion happens and where cohesion happens at each step. It takes about ten minutes and the distinction actually sticks after that. One edge case that came up repeatedly involved the capillary action question. Students would write that capillary action is only about adhesion and lose points. The worksheet specifically wants both forces mentioned. I started requiring them to draw a labeled diagram next to their answer showing the meniscus curve and the upward pull, which forced them to acknowledge both mechanisms. That approach cut down wrong answers on that question by roughly eighty percent in my experience.
The Amoeba Sisters video does not go into depth about pH or the Kw constant, even though those topics sometimes appear on extended worksheets built around the same video. If your teacher added questions about pH, the answer is that pure water has a pH of 7, and the concentration of hydrogen ions equals the concentration of hydroxide ions at that point. The video simply does not cover this material. Another common problem students have is conflating the idea of density with the idea of polarity. These are related but distinct concepts. Polarity causes hydrogen bonding, which causes cohesion and surface tension, which in turn relates to how water behaves physically, including its density anomaly upon freezing. When answering worksheet questions, it helps to keep the chain of causation clear rather than blending everything into one vague explanation about water being special. If you are looking for the actual worksheet file, it is hosted on the Amoeba Sisters website along with the video. The answers listed here align with what the official key provides, though some teachers modify questions slightly. Always double check against your version of the worksheet since question wording can vary between printings and teacher adaptations.
