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A Science lesson on Density





Lori Krawczyk


T321 Lesson Plan

Topic: Sinking vs. Floating

Suggested Grade Level: Grade 5

Concept/Objective: The students will be using the scientific method to test whether or not different shapes made from aluminum foil will either sink or float.

Teaching Materials: Paper and pen to make observations.

Student Materials: approximately 5 small sheets of aluminum foil per group, a balance, a centimeter ruler, a container (500 – mL or larger), graph paper, scissors, water, stopwatches (1 per group of students) or use of a wall clock.

Teacher Background Information: Density is the relationship between an object’s volume and its mass. Volume is the amount of space the object occupies, and mass is a measurement of the amount of stuff in the object, sort of like weight. An object with a lot of mass can have a low density if it is very big, and an object with little mass can have a high density if it is very small. Water has a property called uplift which means that water pushes up against objects that are placed on its surface. Gravity, however, tries to pull the object down through the water, just as uplift tries to push the object back up. If you place something in the water that is less dense than the water, it will float. However, if you drop something into the water that has a mass that is greater than the mass of the water, it will sink. Another background idea is displacement which is what occurs with ships in the water. The ships are made of materials that are denser than water, yet they float. This is because of displacement. The object (ship) is pushing water out of its way. Water doesn’t like being pushed around, so it pushes back against the object, trying to return to the space from which it was pushed. Thus, the effect of the water pushing against the ship makes the ship float.

Management Strategies: For this lesson, I will divide the class into groups of approximately 2 – 3 students who will sit together at small tables with all of the necessary supplies on the table. I would like to have a short discussion with the students at the beginning of the lesson to make introduction. However, I would like for the students to be able to work on their own throughout the rest of the lesson, making inquiries and exploring the different techniques that may be used to establish conclusions. I will allow approximately 20 minutes for this activity in the class (12 minutes in the T321 class), followed by a discussion about the various group results. For obvious safety reasons, I will ask that the students keep any spills or dropped objects cleaned up to avoid slips and falls.

Procedure: To introduce the lesson, I will ask the students to name several objects that both float and sink. I will then ask them to tell me why they think that those specific items float or sink (write down on the board what these items have in common or what their differences are). I will then precede with a very short discussion about density, uplift and displacement. I will then pass out the observation sheet (the other materials will already be placed on the tables). The students will be given the aluminum foil and a tub of water. I will first ask

them to come up with at least three different ways to adjust a single piece of aluminum foil that they feel might make it float and write down their predictions on the designated spot on the sheet. I will then ask them to do the same (3 different ways) for sinking. Once they have written down all of their predictions, I will invite them to test out their predictions that they wrote down through experimentation with the aluminum foil and the water. Throughout the experimentation, I will ask them to keep track of the amount of time that it takes for the aluminum foil object to sink (if it sinks). To do this, they may use any of the supplies that I have rayed out on the table (i.e. the graph paper, the stop watch or clock, the balance, the ruler, etc.) Once they have done the experimentation, I will ask them to write down their procedures and their conclusions on the paper given. I will be reminding them to record all of the data that they collect whether it be on notebook paper or graph paper in the form of charts, tables, diagrams, etc.

Assessment/Evaluation: For evaluating this lesson, I will have the students turn in their data and their observation forms. In addition, on the observation form, I will have a list of questions that the students will answer pertaining to their procedure which will be done on an individual basis.

Extension/Integration: This lesson can be easily integrated into mathematics by having the students measure the rise of the water when a certain number of marbles have been added (in a beaker of water). This would be a great time to reintroduce density and mass. For younger students, this lesson can be simplified and used when doing a unit on boats or on water.

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