If you’re the kind of person who has to fill the sink with water and test it out for yourself, you might want to try these experiments with oranges, limes, lemons, Diet Coke and a few bowling balls. .

Sweet potatoes that float – Sustainable Market Farming

I wrote about growing sweet potato slips previously.Sweet potatoes that float will grow better and yield higher.We had saved 100 roots for a goal of 320 slips.I set the cut roots in shallow bins in our germinating chamber to heal the cut surfaces and warm the roots ready for sprouting.In two weeks I’ll “plant” them in flats of compost and return them to the germinating chamber to start growing the slips.Their propagation method involves cutting each slip into one-node pieces and growing a plant from each short length.This reduces the number of roots to set, which saves propagation space.I searched for more advice and found the Southern Sustainable Agriculture Working Group the previous year had an Organic Farmer Network, who were exchanging tips.Crop planning to rotate crops with different growth habits and timing; neighboring up crops that will have similar cultivation requirements; using the most suitable tractor cultivation equipment; co-ordinating spacing of crops to fit the different equipment (including hands!).and the fact that the biennial nature of brassica seed production means it takes two years to ramp up seed production. .

Sink or Swim: Calculating Density of Fruits and Vegetables

Grab some fruits and vegetables from your kitchen or the grocery store.After you’ve collected your produce, create a hypothesis, your best guess as to what’s going to happen.If the fruit or vegetable sinks, remove the jar from the pan and pour the water into a measuring cup.If the fruit or vegetable floats, push it down with the tip of a pencil until water spills out and over into the pan.For each piece of food, divide the fruit or vegetable’s weight in grams by its volume in milliliters.In a table, make a note of the weight, volume, and density of each fruit or vegetable.Different fruits and vegetables will also float or sink depending on their density.In general, apples, bananas, lemons, oranges, pears, and zucchinis will float, while avocados, potatoes, and mangoes will sink.Whether a fruit or vegetable sinks or floats has a lot to do with its density.Imagine lifting a pillowcase full of feathers.In this experiment, you were trying to find out what vegetables and fruits are the lightweights of the plant world.The shape or age of a fruit can also impact whether it sinks or floats.Water and apples don’t arm wrestle to decide.If your container is completely full when you put the avocado in, the water will spill over the top. .

Sink It

This activity provides an opportunity for students in Grades 3-5 to develop experimental design skills in the context of a familiar event (floating and sinking) while furthering their understanding of the concepts of density and buoyancy.The Benchmarks introduction to the 3-5 Scientific Inquiry also clearly refers to this activity: "They should be encouraged to observe more and more carefully, measure things with increasing accuracy (where the nature of the investigations involves measurement), record data clearly in logs and journals, and communicate their results in charts and simple graphs as well as in prose.Investigations should often be followed up with presentations to the entire class to emphasize the importance of clear communication in science.Class discussions of the procedures and findings can provide the beginnings of scientific argument and debate" (Benchmarks for Science Literacy, p. 11).Finally, students will use a variety of resources to explore how terms such as "buoyancy" and "density" are used to explain the phenomena they have observed.The Way Things Work, by David Macaulay, Houghton Mifflin; ISBN 0-395-42857-2; 1988 has a good section on boats and submarines.Buoyancy Brainteasers, found on the NOVA website has activities and problems to solve on floating and sinking.This should be a quick, fun activity to get students thinking about the properties of the materials (plastic, metals, glass, rubber, wood, etc.).Students can share their classification scheme with the class either through a group discussion, through writings or drawings.This activity uses a phenomenon that is already familiar to most students to help them think about how and why some items float and others sink, and to help them gain skills in gathering data in systematic ways, using a consistent experimental method.Begin by discussing the different ways that students separated their pile of materials into two groups in the introductory activity.Point out that different objects can be described by a number of characteristics, including the type of material from which they are made, their size, their shape, their color, and their weight.Follow this by discussing another characteristic that students may not have considered - whether the objects will float or sink in water.Using the list allow the class to predict whether several demonstration objects (apple, potato, paper clip or penny, and wood piece) will float or sink.You can show several discrepant events of this type to both generate student interest and point out that there is something more to floating and sinking than just weight.Steps should include the recording of data and preparation of the testing tank (bucket) for the next experiment.Students should do a "dry" run, following the steps exactly as they are written, then modify their procedure, if needed.Once their procedure has been approved, students should put the cards in order, run the string through the holes, and tie it loosely.Students can begin their data collection, testing one item at a time, using the steps written on the flip-stack of cards.For purposes of cooperative grouping, one student can serve as the card reader, a second as the equipment handler, and a third as the recorder.Students should retest these items and should add written comments about them on the data table in the "Notes" column.Further explorations of density - comparing volume and weights - will certainly help students expand their understanding of this concept.Students may need to run additional trials with other materials to further test their conclusions.Refer back to the words the students originally used to describe items that float or sink.



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