Mini-Experiments

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What allows insects to walk on water? Melissa Stevenson Many insects are able to walk across water such as water striders. Observing some insects walking on water would lead into a few mini-experiments to discover why certain insects can walk on water, and if these types of insects would be able to walk on all types of water. Through mini-experiments, we will demonstrate what surface tension and a surfactant is so children could have a better understanding of why water striders can walk on water. Water striders legs are shaped to distribute their weight over a larger surface area so that it can better balance on the water. The surface tension of the water is able to support the water strider and prevent the insect from sinking to the bottom. …show more content…

The first mini-experiment would be to visualize surface tension with and without a surfactant. This mini-experiment can be conducted by dropping water one droplet at a time onto a penny and observing what happens (dome water droplet forming) (Kim, 2012). Soap could be added to the water and dropped onto the penny in the same fashion to demonstrate how a surfactant affects the water. The second experiment would demonstrate what it takes to break surface tension. This experiment can be done by observing how many pennies can be carefully added into a cup of water. The children will observe water forming an arc shape over the top of the cup to reduce tension and optimize surface area. The third mini-experiment will test the strength of surface tension by using different shapes of paper clips. The children will experiment to see which shape of paper clip will float on the water (the normal one). This will demonstrate that distributed weight distributed will allow something heavier than water to rest on top of the water due to a strong surface tension (like water striders legs). Through these three mini-experiments, children will observe what surface tension is, how surfactant effect water, and how surface tension allows water strider to …show more content…

•What happened to the water in the cup when pennies were added? Why did the water make an arc shape at the rim? •The water made an arc shape at the rim of the cup. Explain surface tension. Surface tension is something that happen when a liquid such as water molecules is held together tightly. The water molecules especially hold together tightly at the surface because there isn't any water molecules on the other side for them to grab onto. The water molecules at the surface hold together so tightly that a film/skin forms at the surface of the water creating a dome. Experiment 2: Visualizing surface tension with and without a surfactant •Were you surprised by the amount of water drops the penny could hold? Why do you think it could hold as many drops as it did? •Explain surface tension like in experiment 1. •Could you add more or less water drops to the penny with soapy water? Why? •Soap is a surfactant which reduces surface tension of water. The soap is interfering with the water molecules ability to hold together tightly causing th surface tension to be

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