6/30/03Prof. Lynn Cominsky1 Properties of Matter Professor Lynn Cominsky Joanne del Corral Al...

6/30/03 Prof. Lynn Cominsky 1

Properties of Matter

Professor Lynn CominskyJoanne del Corral

Al JanulawMichelle Curtis

NBSP Physical Science Leadership Institute

June 30, 2003


Standard Connections

Properties of matter can be observed, measured and predicted (K)

As a basis for understanding this concept, students know that objects can be described…on the basis of physical properties such as WEIGHT

What are the common properties that scientists use to describe matter?


First Activity: Measuring matterHow do we measure mass?How do we know when 2 objects have the same mass?

Assemble a balance. Sketch it in your notes, and label the parts of the balance.

Experiment with the objects to see how the balance operates.


Equipment for Measuring matter activity

Plastic balance

Pans

Set of random objects

Lots of washers


Further investigations:

Does it make a difference where the objects are placed in the pans?Does it make a difference if you switch the objects and place them in different pans?Does it make a difference if you use a different balance?What does it mean when we say something is in balance?


Operational DefinitionsAn operational definition describes the process that is used to make a measurementIt should be able to be used by another individual to repeat the measurement process using the same (or similar) equipment


Questions for the mass activity #2:

How do we establish a set of standard masses?Can you write an operational definition for mass?

Equipment for the mass activity #2:

Small pan balancesStandard mass sets


Mass activity #2Use washers to measure the mass of an object in your setMeasure the mass of a single washer using the standard mass setMeasure the object using the standard mass set – did the results make sense?Use the standard mass set to measure a different objectPredict how many washers it would take to balance this object – did it work?


Thought experimentFirst weigh one object, and then weigh a second object.If you now put both objects on the scale at the same time, how will the total mass compare to the sum of your first two measurements?


Key concepts: MassMass is a property of matter that can be measured using a standard set of objects. The typical standard that is used to measure mass is the gram.In most everyday situations, mass is conserved. M1 + M2 = M1+2


Vocabulary

Equal-arm Balance: a physical instrument used to measure mass by comparing items Mass:property of matter that describes its quantityGram:standard unit of measurement for massStandard mass set: Set of masses which have a known relationship to one anotherWeight: result of gravity acting on mass


ELD Activities: CompareCompare and contrast masses of different objects in the classroomMake a table with descriptions to help remember new words:

Object Mass Object Description


Publisher’s Materials

Take some time to look through the state-adopted texts to find activities relating to measuring and observing objectsExamples: HC p. C5


Break – some things to think about

What is the difference between mass and weight?How would your mass change if you lived on the Moon? How would your weight change?


Standard ConnectionsStudents know that objects can be described…on the basis of physical properties such as shape (K)

How do we measure volume?How do we know when 2 objects have the same volume?How does measuring volume compare to measuring mass?


Third Activity – Volume of a Solid Given: a large block and lots of smaller cubesUse the cubes to make a model of the large blockCount the number of cubes that it takes to make your modelRepeat for several different objectsIs volume always = length x width x height?


Fourth activity: Volume and Liquid

How do we measure the volume using a liquid?What is the relationship between 1 cm3 and 1 mL?

Graduated cylindersWaterPlastic cubes and other objects

Equipment for Fourth activity


Graduated CylindersReading is taken by reading the bottom of the meniscus at eye levelWhat is this reading?


Fourth activity: Volume and Liquid

Fill the graduated cylinder to the 35 mL mark. Drop in 7 of the plastic cubes. Measure each cube with a ruler.How much does the water level rise?How could you put marks on the side of the cylinder if they were not already there?Write an operational definition for volume


More questions about volume and mass:

How would you measure the volume of an irregularly shaped object if it was too large to fit into a graduated cylinder?Does each gram of a submerged object displace a gram of water?Could we measure the mass of a submerged object by the water displacement method?


Thought experimentSuppose a graduated cylinder is filled up to the 50 mL mark with dry sand. Then suppose that 30 mL of water is poured into the cylinder. Will the final volume of the water and sand be measured at 80 mL? Explain your reasoning.


Thought experiment #2

There are at least two volumes associated with a tin can.What are they and how would you measure each?


Key concepts: Volume

Volume – is measured using a standard set of objects such as uniform cubes, or by measuring a liquid such as water, which is displaced by the object to be measuredVolume is NOT conserved: V1 + V2 is not necessarily equal to V1+2


Volume: the amount of space that an object displacesGraduated Cylinder: A physical instrument used to measure volume of liquids (directly) or of solids (by submersion)

Vocabulary


ELD Activities: Analogies and Student Involvement

Draw a few circles of different sizes on the ground; tell the student the circles represent cylinders. Then ask the students to stand in one of the circles until each circle is full. Let them count how many students are in each circle once everyone has a place.



Take some time to look through the state-adopted texts to find activities relating to measuring volume that could be used in your classroom.


Lunch break - Things to think about

Consider the two boxes shown. Their dimensions are given in meters. Answer the following questions about the boxes. Explain your reasoning.

36

22

3

3

Box A Box B


Lunch break questions:Suppose these boxes, including their lids, are made of very thin plywood. Which box requires more wood?Which box will hold more peanuts?Which box is heavier (empty)?Which box would you say is bigger and why?


Standard ConnectionsStudents know that objects can be described…on the basis of physical properties such as floating & sinking (K)

How do we measure density?How can we tell if an object will sink or float?


Key concepts: density

Density is defined as the mass of an object divided by its volumeDensity is a characteristic property of an object: under the same conditions, all objects made of the same material have the same densityThe units for density are g/cm3 – The value tells you how many grams are in one cubic centimeter of material


Thought experiment: Density

A block of wood has a mass of 18 g and a volume of 25 cm3

How would you interpret the number 18/25?How would you interpret the number 25/18?Write an operational definition for density


Standard ConnectionsStudents know density is mass per unit volume (8)Students know how to calculate the density of substances (regular and irregular solids and liquids) from measurements of mass and volume (8)


Fifth Activity: Sinking and Floating

Given: a set of objects, and a beaker of water. Predict whether your objects will sink or float, then test out your predictionsCan you turn any sinkers into floaters? Floaters into sinkers?Separate the sinkers and floaters into separate groups


Fifth Activity: Sinking and Floating

What similarities are there among the objects that floated? What differences?What similarities are there among the objects that sank? What differences?Make a list of things that you believe influence whether or not an object can floatHow will you test your ideas about sinking and floating?


Standard ConnectionsAll objects experience a buoyant force when immersed in a fluid. As a basis for understanding this concept:

Students know the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced (8)Students know how to predict whether an object will float or sink (8)


Sixth activity: When does a boat float?

Given: little boat made of plastic cubes, aluminum foil and tape, pennies, scale, pan of water, rulerMeasure the mass of the boatCan you use the water submersion method to determine the volume of the boat? Why or why not?

Measure the volume of the boat (including cargo space)


Sixth activity: When does a boat float?

Calculate the average density of the boatGiven: the density of water is 1 gm/cm3

Weigh 10 pennies, then calculate the average weight of one pennyPredict how many pennies you can add to the boat before it will sink.Test out your prediction.What do you conclude?


Key concepts: Sinking and Floating

When an object is totally submerged in a liquid, it displaces a volume of the liquid equal to its volumeIf the object is floating in a liquid, it displaces a volume of the liquid which has the same mass as the entire objectIf you know the density of both the object and the liquid, you can calculate how much of the object is submerged in the liquid


Math connectionsAn ice cube with volume of 1 cm3 has a density of 0.9 g/cm3

It is floating in very salty water that has a density of 1.2 g/cm3

What is the mass of the ice cube?What is the mass of the salty water that it displaces?What is the volume of the water that it displaces?How much of the ice cube floats above the water?


Cartesian Diver revisitedCan you now explain the observations that you made in this activity?Another way to do this experiment is with a sealed packet of ketchup (that contains a trapped air bubble), rather than an eye dropper. What do you think would happen if you did this experiment at a different temperature? A different altitude?Would the same things happen if you used the eye dropper instead of the ketchup?


VocabularySinking: when an object is entirely covered with liquid

Floating: when only part of the object is covered with liquid


ELD Activities: Academic Language

When someone is slow to understand, they may be called dense. Why?When someone is feeling sad, they are said to have a sinking feeling. Why?When someone is feeling happy, they are said to be floating on air. Why?



Take some time to look through the state-adopted texts to find activities relating to sinking and floating that could be used in your classroom.Examples: HM p. 198, HM p. C7


Break – puzzler

You are sitting in a boat which is floating in a small pond. Next to you, inside the boat, is a large rock. The density of this rock is 10 g/cm3. You pick up the rock and throw it over the side of the boat. Does the water level in the pond go up, stay the same or go down? Explain your answer.


Standard ConnectionsStudents know that objects can be described…on the basis of physical properties such as ATTRACTION TO MAGNETS

What types of materials are attracted to magnets?How can we tell the difference between a magnet and a metal?Are any materials repelled from magnets?


Equipment for third activityMagnets of various sizes and shapesSome pieces of non-magnetized metalOther things like rubber, wood, glass, plastic, aluminum, paper clips, etc.

Seventh activity: Exploring magnets

Use different magnets and bag of objects to explore magnetic properties


A few things to try:

Bring pairs of like and unlike magnets together at different locationsPlay with magnets and pieces of metal like paper clipsPlay with magnets and other materialsWhat common properties do objects have that are attracted to magnets?Some things on your own!


Key conceptsMaterials that are attracted to magnets are metalsMagnets are both attracted and repelled from other magnetsSome metals are more strongly magnetic than others – iron is typically used for magnetsSome parts of the magnet (poles) are more magnetic than others


VocabularyMagnet: material that can both attract and Magnet: material that can both attract and repel other magnets. Iron is most common.repel other magnets. Iron is most common.

Pole: Part of the magnet where the force is Pole: Part of the magnet where the force is the strongestthe strongest

Metal: material that is often attracted to Metal: material that is often attracted to magnets and a good electrical conductormagnets and a good electrical conductor

Horseshoe magnet: Horseshoe magnet:

U-shaped magnetU-shaped magnet

NS


ELD Activities: Visual Imagery

Make a list of objects that you have tested for magnetic propertiesIndicate whether or not they were attracted to the magnetDraw a picture of each objectExamples could include: paper clip, pencil, paper. Others?Item Attracted? Drawing



Take some time to look through the state-adopted texts to find activities relating to magnets that could be used in your classroom.Examples: HC p. C38


Take away – brain teaser

Someone gives you 2 bars of identical shape, weight and appearance One is a magnet and the other one is metalHow can you tell which is which? (You can’t use any other equipment, you can’t touch the bars to anything but each other and you don’t know which way North is located.)?


Lesson Study Activities

Identify a key concept from today’s lecture for further developmentReview the publisher’s materials about this key concept Think about the best way to present this key concept in your classroom


Resources

Physics by Inquiry – L. McDermott and the PEG at U Washingtonhttp://littleshop.physics.colostate.edu/Cart.htmlhttp://chemscape.santafe.cc.fl.us/chemscape/catofp/measurea/volume/gradcyl/gradcyl.htm

6/30/03Prof. Lynn Cominsky1 Properties of Matter Professor Lynn Cominsky Joanne del Corral Al...

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