1. Properties of Matter Professor Lynn Cominsky Joanne del Corral
Al Janulaw
Michelle Curtis
NBSP Physical Science Leadership Institute
June 30, 2003
6/30/03
Prof. Lynn Cominsky

2. 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?
6/30/03
Prof. Lynn Cominsky

3. First Activity: Measuring matter
How 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.
6/30/03
Prof. Lynn Cominsky

4. Equipment for Measuring matter activity
Plastic balance
Pans
Set of random objects
Lots of washers
6/30/03
Prof. Lynn Cominsky

5. 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?
6/30/03
Prof. Lynn Cominsky

6. Operational Definitions
An operational definition describes the process that is used to make a measurement
It should be able to be used by another individual to repeat the measurement process using the same (or similar) equipment
6/30/03
Prof. Lynn Cominsky

7. Questions for the mass activity #2:
Equipment for the mass activity #2:
Small pan balances
Standard mass sets
Questions for the mass activity #2:
How do we establish a set of standard masses?
Can you write an operational definition for mass?
6/30/03
Prof. Lynn Cominsky

8. Mass activity #2
Use washers to measure the mass of an object in your set
Measure the mass of a single washer using the standard mass set
Measure the object using the standard mass set – did the results make sense?
Use the standard mass set to measure a different object
Predict how many washers it would take to balance this object – did it work?
6/30/03
Prof. Lynn Cominsky

9. Thought experiment
First 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?
6/30/03
Prof. Lynn Cominsky

10. Key concepts: Mass
Mass 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
6/30/03
Prof. Lynn Cominsky

11. Vocabulary
Equal-arm Balance: a physical instrument used to measure mass by comparing items
Mass:property of matter that describes its quantity
Gram:standard unit of measurement for mass
Standard mass set: Set of masses which have a known relationship to one another
Weight: result of gravity acting on mass
6/30/03
Prof. Lynn Cominsky

12. ELD Activities: Compare
Compare and contrast masses of different objects in the classroom
Make a table with descriptions to help remember new words:
Object Mass Object Description
6/30/03
Prof. Lynn Cominsky

13. Publisher’s Materials
Take some time to look through the state-adopted texts to find activities relating to measuring and observing objects
Examples: HC p. C5
6/30/03
Prof. Lynn Cominsky

14. 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?
6/30/03
Prof. Lynn Cominsky

15. Standard Connections
Students 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?
6/30/03
Prof. Lynn Cominsky

16. Third Activity – Volume of a Solid
Given: a large block and lots of smaller cubes
Use the cubes to make a model of the large block
Count the number of cubes that it takes to make your model
Repeat for several different objects
Is volume always = length x width x height?
6/30/03
Prof. Lynn Cominsky

17. Fourth activity: Volume and Liquid
How do we measure the volume using a liquid?
What is the relationship between 1 cm3 and 1 mL?
Equipment for Fourth activity
Graduated cylinders
Water
Plastic cubes and other objects
6/30/03
Prof. Lynn Cominsky

18. Graduated Cylinders
Reading is taken by reading the bottom of the meniscus at eye level
What is this reading?
Answer: 52.8 mL
6/30/03
Prof. Lynn Cominsky

19. 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
6/30/03
Prof. Lynn Cominsky

20. 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?
6/30/03
Prof. Lynn Cominsky

21. Thought experiment
Suppose 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.
6/30/03
Prof. Lynn Cominsky

22. Thought experiment #2
There are at least two volumes associated with a tin can.
What are they and how would you measure each?
6/30/03
Prof. Lynn Cominsky

23. 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 measured
Volume is NOT conserved: V1 + V2 is not necessarily equal to V1+2
6/30/03
Prof. Lynn Cominsky

24. Vocabulary Volume: the amount of space that an object displaces
Graduated Cylinder: A physical instrument used to measure volume of liquids (directly) or of solids (by submersion)
6/30/03
Prof. Lynn Cominsky

25. 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.
6/30/03
Prof. Lynn Cominsky

26. Publisher’s Materials
Take some time to look through the state-adopted texts to find activities relating to measuring volume that could be used in your classroom.
6/30/03
Prof. Lynn Cominsky

27. 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. 3
Box B 2
Box A 2 3 6 3
6/30/03
Prof. Lynn Cominsky

28. 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?
6/30/03
Prof. Lynn Cominsky

29. Standard Connections
Students 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?
6/30/03
Prof. Lynn Cominsky

30. Key concepts: density
Density is defined as the mass of an object divided by its volume
Density is a characteristic property of an object: under the same conditions, all objects made of the same material have the same density
The units for density are g/cm3 – The value tells you how many grams are in one cubic centimeter of material
6/30/03
Prof. Lynn Cominsky

31. 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
6/30/03
Prof. Lynn Cominsky

32. Standard Connections Students 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)
6/30/03
Prof. Lynn Cominsky

33. 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 predictions
Can you turn any sinkers into floaters? Floaters into sinkers?
Separate the sinkers and floaters into separate groups
6/30/03
Prof. Lynn Cominsky

34. 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 float
How will you test your ideas about sinking and floating?
6/30/03
Prof. Lynn Cominsky

35. Standard Connections
All 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)
6/30/03
Prof. Lynn Cominsky

36. Sixth activity: When does a boat float?
Given: little boat made of plastic cubes, aluminum foil and tape, pennies, scale, pan of water, ruler
Measure the mass of the boat
Can 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)
Use post-1982 pennies at 2.5 g each.
Boats will sink with about 8 or 9 pennies. (They are all slightly different due to the aluminum foil and tape.)
6/30/03
Prof. Lynn Cominsky

37. Sixth activity: When does a boat float?
Calculate the average density of the boat
Given: the density of water is 1 gm/cm3
Weigh 10 pennies, then calculate the average weight of one penny
Predict how many pennies you can add to the boat before it will sink.
Test out your prediction.
What do you conclude?
6/30/03
Prof. Lynn Cominsky

38. Key concepts: Sinking and Floating
When an object is totally submerged in a liquid, it displaces a volume of the liquid equal to its volume
If the object is floating in a liquid, it displaces a volume of the liquid which has the same mass as the entire object
If you know the density of both the object and the liquid, you can calculate how much of the object is submerged in the liquid
6/30/03
Prof. Lynn Cominsky

39. Math connections
An 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?
6/30/03
Prof. Lynn Cominsky

40. Cartesian Diver revisited
Can 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?
6/30/03
Prof. Lynn Cominsky

41. Vocabulary Sinking: when an object is entirely covered with liquid
Floating: when only part of the object is covered with liquid
6/30/03
Prof. Lynn Cominsky

42. 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?
6/30/03
Prof. Lynn Cominsky

43. Publisher’s Materials
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
6/30/03
Prof. Lynn Cominsky

44. 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.
When it is in the boat, it is floating, so the rock is displacing 10 mL of water (assuming it is a 10 g rock.)
When it is put in the water, it is sinking, so then it only displaces 1 mL of water.
As a result the water level in the pond goes down.
6/30/03
Prof. Lynn Cominsky

45. Standard Connections
Students 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?
6/30/03
Prof. Lynn Cominsky

46. Equipment for third activity
Seventh activity: Exploring magnets
Use different magnets and bag of objects to explore magnetic properties
Equipment for third activity
Magnets of various sizes and shapes
Some pieces of non-magnetized metal
Other things like rubber, wood, glass, plastic, aluminum, paper clips, etc.
6/30/03
Prof. Lynn Cominsky

47. A few things to try:
Bring pairs of like and unlike magnets together at different locations
Play with magnets and pieces of metal like paper clips
Play with magnets and other materials
What common properties do objects have that are attracted to magnets?
Some things on your own!
6/30/03
Prof. Lynn Cominsky

48. Key concepts Materials that are attracted to magnets are metals
Magnets are both attracted and repelled from other magnets
Some metals are more strongly magnetic than others – iron is typically used for magnets
Some parts of the magnet (poles) are more magnetic than others
6/30/03
Prof. Lynn Cominsky

49. Vocabulary
Magnet: material that can both attract and repel other magnets. Iron is most common.
Pole: Part of the magnet where the force is the strongest
Metal: material that is often attracted to magnets and a good electrical conductor
Horseshoe magnet:
U-shaped magnet N S
6/30/03
Prof. Lynn Cominsky

50. ELD Activities: Visual Imagery
Make a list of objects that you have tested for magnetic properties
Indicate whether or not they were attracted to the magnet
Draw a picture of each object
Examples could include: paper clip, pencil, paper. Others?
Item Attracted? Drawing
6/30/03
Prof. Lynn Cominsky

51. Publisher’s Materials
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
6/30/03
Prof. Lynn Cominsky

52. Take away – brain teaser
Someone gives you 2 bars of identical shape, weight and appearance
One is a magnet and the other one is metal
How 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.)
The magnet will be attracted to all parts of the metal bar.
The metal bar will only be attracted to the polar ends of the magnet, and not to its center. ?
6/30/03
Prof. Lynn Cominsky

53. Lesson Study Activities
Identify a key concept from today’s lecture for further development
Review the publisher’s materials about this key concept
Think about the best way to present this key concept in your classroom
6/30/03
Prof. Lynn Cominsky

54. Resources
Physics by Inquiry – L. McDermott and the PEG at U Washington
6/30/03
Prof. Lynn Cominsky