PS1+(7-8)+-+1


 * -Students demonstrate an understanding of characteristic properties of matter by …**

1a measuring mass and volume of both regular and irregular objects and using those values as well as the relationship __D=m/v to calculate density__

What do these GSEs mean? What subtopics do students need to address to understand these GSEs?
__meaning of the GSE__ a cube of copper has more mass (weighs more) than same size cube of aluminum a cube of aluminum has more mass (weighs more) than same size cube of plastic
 * This GSE wants the student to be able to understand density and why it is an important characteristic of matter.
 * According to this GSE through experimentation the student should have a better understanding of the equation D= m/v and be able to use the values obtained in the experiment to calculate the density of the object using the equation
 * This GSE connects the concept learned in PS1(5-6)-1, the student being able to understand characteristic properties of matter through comparison of different objects of the same volume, and the being able to use the characteristic of density to identify and unknown substance, which is what PS1(9-11)-1 requires.
 * Students in younger grades compare objects that are all the same volume but different materials. They find, for example:
 * a cube of lead has more mass (weighs more) than same size cube of copper

> we must also point out that some different materials could have the same density; therefore determining d can rule out some choices (e.g. this is not dense enough to be lead) but not enough for the final choice. As that GSE says, one might need several properties to make the right choice, such as density, specific heat, and electrical conductivity.
 * through GSE PS1(7-8)-1 students should be taking the information learned from the PS1(5-6)-1 GSE and have a greater understanding of why it is an important characteristic of matter and make connection with the calculation of density through the measure quantities of volume. Students will find for the next level of understanding that different size and shaped objects of a given material of course have different mass (weight) but when they compute d=m/v they are the same, thus density is a property of the material.
 * In GSE PS1(9-11) students use the fact that density is a property of a material) as a way to identify materials, measuring m and v to get d for a sample to suggest what it is made of. At this level

__subtopics needed to be understood__
 * mass is the measure of how much of something is present. samples of different materials may happen to have the same mass, and different size samples of the same material will have different masses.
 * volume is a measure of space, or the space occupied by something. a rectangular container such as an aquarium has a volume of L x W x H, but a container of some other shape may have the same volume.
 * volume of regular objects( cubes, cylinders...)
 * cube = a 3 , where a is the length of one side
 * cylinder = πr 2 h
 * pyramid = 1/3 Bh where B is the area of the base (l x w)
 * cone = 1/3 πr 2 h
 * determining the volume of irregular objects with water displacement
 * measuring the volume of just the water, without the object in the graduated cylinder and the volume of water with the object in the graduated cylinder, then taking the final volume with the object and water and subtracting the volume of just the water.
 * measuring the weight change (buoyancy) due to the water displacement may be easier than directly measuring the displacement volume. There are two ways to do this. Either put a container of water on the scale, weigh it, then lower the object into it, and note the weight increase, which equals the buoyant force. Or, have the object hanging from a scale, that one would decrease by the same amount the first one increased. Either scale gives the same change in weight, one is plus the other is minus. Knowing the density of water, this gives the displacement volume.


 * To determine the density of a liquid, the mass and volume of a sample are easily measured; first weigh an empty graduated cyclinder, then fill it and weigh it again to note the increase. The corresponding mass divided by the volume gives the density.

What ideas to students need to understand before they can address the topics described above?

 * measuring mass
 * what equipment is used for measuring mass
 * why does the scale need to be tared before weighing the object.
 * calculating volume with the use of equations
 * 1cm 3 ﻿= 1mL, Liters are commonly used by the U.S., but the official SI unit (metric) for volume is cubic centimeters and is used most commonly in the field of science.
 * Measuring volume
 * what a meniscus is and what it is used for
 * what is the equipment used for measuring volume

What misconceptions are students likely to have about these topics?

 * mass is weight
 * density is the thickness of an object
 * the heaviness of an object determines whether it will sink or float

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What phenomena and representations help students understand these topics?
> media type="youtube" key="7HNMiUH1Xkk?fs=1" height="385" width="480"
 * comparing the density of ice to the density of water
 * mass doesn't change but the weight of an object does depending on the gravity involved with the object.
 * This You Tube Video is called "Density Rainbow". It goes through an activity in which students can see density through an activity in which they make cups of sugar water each containing one more spoon of sugar than the one before.. They could then pour some of each into a graduated cylinder or use the straw method shown in the video. This is a great visual way for the students to see the different densities of the liquids containing different amounts of sugar.
 * "Density Rainbow." //You Tube//. Web. 11 Oct 2010. 


 * **What activities or activity sequences can be used to address these GSEs?**
 * This is a You Tube video of a demonstration of gravity that could be made into an activity that students could perform. The teacher could first demonstrate using the regular and diet soda and then the students could find the mass of the soda and the volume of the can by using water displacement. The students could then use their data to calculate the density of each can of soda using the formula, d=m/v.

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"ScienceBoom Episode #1 - Density Demonstration."//You Tube//. Web. 11 Oct 2010. .

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