INTRODUCTION (Click on the balloon to see the full activity and any associated labs)

1 Up, Up and Away: Building a Hot Air Balloon

The question of how a hot air balloon works sets the context for making the connection between the micro and macro scale worlds. (physical lab)

In this activity students investigate the question: "How does a hot air balloon work?" Students begin by building small hot air balloons and then launching them. Students then discuss how they think a hot air balloon floats. Finally, students are introduced to the use of models as a tool for understanding.

2 The Power of Thinking in Powers of Ten

Understanding the microscopic world of atoms requires having some sense of scale to compare the visual world to that of the tiny atom. (computer lab)

Students use Workbench software to get a visual sense of the relationship between powers of ten and objects of that size.

Then students go to a web site where they can do virtual electron microscopy. While observing various items with their virtual electron microscope students are asked to indicate how many orders of magnitude difference there are between the lowest and highest power magnification.

3 Have You Seen an Atom Lately?

Everything is made of atoms. (Physical lab)

In this activity students investigate the question: "What is matter and what is it made of?" Students debate the merits of two opposing views of matter and then conduct two experiments to provide evidence for one or the other view. Students then conduct two experiments:

1. Observing the spreading of a drop of oil on water.
2. Mixing a measured amount of alcohol and water.

The results of these experiments will be used to support one of the views of matter. Then a demo is performed in which is an analogy of the second experiment by combining stones and sand.

Finally, students view some images created with a Scanning Tunneling Microscopes (STM) that represent atom locations.

MODELING MACRO AND MICRO

4 Superballs are Like Atoms

Rubber balls have properties, like elasticity ["bounciness"] and kinetic energy [energy of motion] which can be converted into other forms of energy. (Physical lab)

Students discuss varying forms of energy and how one form can be converted into another.
They then experiment with superballs to observe their behavior by dropping them and rolling them toward other objects to see how much they can push another object before coming to rest. Observations of varying elasticity [“bounciness”] and kinetic energy [energy of motion] due to differences in velocity [speed] and mass are be made.

5 Modeling Microworlds

Models can be used to help us understand and predict the behavior of super balls and atoms. (kinesthetic lab and computer lab)

Part A: An explanation of how modeling can take different forms is given. Then students play the role of superballs in their first kinesthetic modeling experience.

Part B: Using Workbench software students interact with a computer model of a super ball. They will have the ability to "throw" or launch the ball around the box and be able to modify various properties, such as the mass of the ball, initial speed of the ball, and elasticity of its collision with the walls. Then, using ZoomIt, students zoom in from outer space down through the powers of ten to the atomic level where they find a single atom contained in a box.

6 It Takes Two to Tango: Modeling Two Atoms in a Box

Collisions between two atoms results in a transfer of kinetic energy [energy of motion] from one atom to the other, and demonstrates that the total kinetic energy of the two atoms is the same before and after the collision. (Computer lab)

Students use Workbench software to observe and measure the interaction between two atoms. By colliding atoms and graphing their kinetic energy, they learn that total kinetic energy is conserved.

7 Feeling Low on Energy? Have Some of Mine

Continual movement of atoms results in motion that looks random and causes kinetic energy to be distributed evenly among the atoms in a gas. (Kinesthetic lab and computer lab)

Part A: Students will kinesthetically model a gas, by moving around as atoms which can exchange kinetic energy. By doing this they will get a firsthand view of what an atom "experiences" when it is bouncing around a container with lots of other atoms.

Part B: Students will then observe a model of a gas (in spatial and thermal equilibrium) on the computer, experimenting with varying initial conditions (# of atoms, masses of atoms, initial velocity of atoms) to see what kind of predictions the model makes about the eventual state of the total system and each individual atom. They should eventually observe that the kinetic energy [energy of motion] is distributed evenly among atoms and comes to a state of equilibrium.

DIFFUSION

8 A Matter of Stating the State of Matter

The compressibility of a substance indicates the space, or lack of it, between the atoms or molecules of various states of matter. (Physical and computer lab)

Part A: Students put air and then water in a sealed syringe. In each case they try to compress the substance, and then discuss why gas is compressible and liquid is not.

Part B: Students view a computer model of a solid, a liquid, and a gas, and then discuss how this model helps to explain their previous experiment.

9 Wow! How did that smell get over here?

Gas will diffuse through a room at an equal rate in all directions from the point where it is released. (Physical and computer lab)

A bottle full of a pungent gas, either perfume or ammonia, is opened, and students consider how to explain the diffusion of the odor throughout the room. They use both writing and kinesthetic modeling to express their ideas.

10 On Your Marks. Get Set. Go! ... A Molecular Race

If mixed together, molecules with various masses will move at different speeds related to their mass. (Computer lab)

Part A: Students observe a demonstration in which two gasses placed in opposite ends of a sealed glass tube, encounter one another and form a white powder or a cloud.

Part B: Students use a computer model to represent the same behavior of various gasses in a glass tube.

11 Molecular Rematch: Heavyweight vs. Lightweight Championship Race

Atoms with various masses will move at different speeds related to their mass if mixed together. (Physical lab and computer lab)

Part A: Students put a small amount of lead nitrate solution on one side of a petri dish and potassium iodide solution on the other side. They then observe a reaction between the lead ion and the iodide ion, forming a yellow precipitate.

HEAT AND TEMPERATURE

12 Shake it Up Baby - Crank the Heat

Temperature is a measure of the average kinetic energy of the atoms of a substance while heat is the total kinetic energy of those atoms. (Computer lab)

Students use a computer simulation to discover the connection between temperature and kinetic energy [energy of motion]. The computer simulation shows a box divided into two sections by a wall that can be removed. Students can then fill either side of the box with molecules of varying mass. They can also adjust the temperature of either box. Graphs show the average kinetic energy of atoms in each partition. Students are asked to experiment with the various options for adjusting the temperature and/or mass in either partition. Students can also remove the partition so that atoms from either side can mix.

13 Cool It! ... Especially if You're Hotter Than Me

Heat energy can be transferred between two containers by putting them in direct physical contact, and this heat energy will always flow from the hotter container to the cooler container. (physical, kinesthetic, and computer lab)

Part A: Students fill two containers (plastic bags) with water of different temperature, insert a temperature probe into each bag and monitor the temperature on the computer. Students then repeat the experiment, but put the bags in contact with each other.

Part B: Students kinesthetically model the lab from Part A.

Part C: Based on the students’ previous experience with the kinesthetic modeling of heat transfer between two containers in direct contact, students are predict what the computer model would look like for this situation. They then use a computer simulation of the lab in Part A. Students then compare and contrast their previous kinesthetic experience, with their prediction and actual experience with the computer model.

GAS PRESSURE

14 Don’t Be so Pushy ... Oh, You’re a Gas. That’s OK.

Gas pressure is a function of the frequency and force of impacts of molecules distributed over a certain area. (Physical and computer lab)

Part A: Students place a balloon on an empty two liter soda bottle, and then observe what happens when heated and cooled by placing the bottle in a hot and cold water bath. They then discuss what they think is happening.

Part B: Students use Workbench software to experiment with a contained gas. They experiment with changes in pressure, temperature, and volume, and discuss their observations.

15 You Can’t Vacuum the Moon

Suction, which is usually thought of as a pulling force, does not exist. (Computer lab)

Part A: A classic demonstration is done in which the “suction force” causes two plates or hemispheres to stick together. Students then discuss why they stick together. They then kinesthetically model why air gets "sucked" back in when the valve sealing the two plates is opened.

Part B: More demonstrations are done, each one discussed to explain how the visual result can occur through a pushing force, not the previous false notion of a pulling “suction force”.

PHASE CHANGES

16 We Have to Stick Together ... We’re Molecules

There is an attractive force between all atoms, causing or preventing phase changes and resulting in specific melting and boiling points. (Computer lab)

Class begins with a discussion about the necessity of changing the model to accommodate attractive forces between atoms and why this is needed to model phase changes. Students then use a computer model to visualize phase changes and understand boiling points (due to van der Waals attractions).

17 Give Me Some Space - I’m Boiling Over

Substances in the gas phase take up much more room than that same substance in the liquid or solid phase. (Physical lab)

Students put a balloon on two different test tubes, one containing just air, the other with a small amount of water. Students then heat the test tubes and observe which one causes the balloon to inflate more. They then boil a small amount of water in an open test tube, and place a balloon on the top just as the test tube is removed from the heat.

18 Rainstorm in a Bag

The cycle of boiling, cooling, and condensing can be observed in a ziplock bag, using a liquid with the appropriate boiling point. (Physical lab)

Students put some butane in a ziplock bag, observe it boil and then inflate the bag. Then students place some dry ice on the bag and observe the cycle of condensation and boiling that occurs.?

DENSITY AND BUOYANCY (HOT AIR BALLOON CONCLUSION)

19 Don’t be So Dense - You Might Sink to the Bottom, or, How Do Whales Dive So Deep?

Density is a description of how much mass is crammed into how small a space. (Computer lab)

Part A: The students observe several plastic soda bottles filled with various substances and discuss the varying density of those substances. After being given the numerical density of each substance the students observe while some are placed in an aquarium tank filled with water. After the first observations, students are asked to predict whether the next couple of bottles will sink or float.

Part B: Students use the computer to measure the density of various combinations of atoms with varying mass and varying space between the atoms.

20 Floating on Air

Any type of balloon that floats, does so because it contains a gas that is less dense than the surrounding air. (Computer lab)

Part A: A demonstration is done showing the different densities of gases by filling one balloon with CO₂ and another with He. The helium balloon floats and the CO₂ balloon sinks. Students then use a computer simulation to understand different ways to achieve different densities.

Part B: Students use Workbench software to see the effect of heating air inside a balloon and causing it to float away.

They will be asked to use all that they have learned during this unit to describe how a balloon flies and the environment around the balloon as it ascends into the atmosphere as high as the clouds. They will have to explain everything at both a macroscopic and microscopic level.