5 - Exploring Water with Star Wars
This lesson plan focuses on NGSS 5-PS1 and can extend to 5-PS2.B or 5-ESS2, and includes finding averages and looking for article credibility.
- Play one or both of these clips from George Lucas’s Star Wars: Episode I - The Phantom Menace
- Discuss. What did you see? What do you wonder?
- The most important thing to notice is how the film surrounding the building behaves as Obi-Wan, Qui-Gon, and Jar Jar Binks go through it (first 15 seconds of both videos)
Experiment - Drops on a Penny
- Objective: To observe and explore polarity and surface tension as exhibited by water molecules.
- Materials: pennies, water, disposable pipets, paper towels
Lecture and Discussion Points (5-PS2)
- Matter is anything that takes up mass and volume
- Matter can be divided into particles too small to see, called atoms
- Atoms are the “stuff” that makes up everything and are the smallest unit in the universe!
- There are about 30,120,000,000,000,000,000,000 atoms in one grain of sand!
- “Atom” is from the Greek word atomos meaning “uncuttable”
- Groups of atoms are called molecules
- Some examples of molecules you may have heard of are caffeine (C8H10N4O2) and carbon dioxide (CO2)
- Water is a molecule (see right) with the formula H2O
- It has 2 hydrogen atoms and one oxygen atom
- Water is polar, meaning that there is a region of slight positive charge and slight negative charge.
- Polarity allows liquid water to form through cohesion.
- *tip* A good demonstration of this would be to put one drop of water on the penny, then another drop of water just touching it. Notice how the drops “stick” together. This is cohesion at work.
- Hydrogen bonds are formed by the hydrogen atoms of one molecule being attracted to the oxygen atoms of another molecule. In other words, the negative region around the oxygen is attracted to the positive region around the hydrogen.
- Surface tension is a special term we use to describe the cohesion between water molecules compared to their surroundings. Water has especially high surface tension because of its hydrogen bonds.
- The water molecules are more attracted to each other than they are to the air or any surface.
- This creates the spherical shape of water droplets; the shape evenly maximizes the distance between same-charged atoms
- Surface tension is what allows the bubble of water to form on the penny.
- Extension: Try or demonstrate the same experiment with oil.
- Oil is non-polar, meaning that it does not have positive and negative regions and thus, does not have hydrogen-bonding. Thus, it has almost no surface tension.
Conclusion - Star Wars
- Qui-Gon, Obi-Wan, and Jar Jar are able to go through the “bubble” and the “bubble” returns to its original shape because of surface tension! You can actually see the surface tension against Obi-Wan’s face as he enters (first clip from link).
- This is especially true because the buildings that the “bubble” surrounds is filled with air. Air is also filled with atoms and molecules (like N2, water, CO2, etc.), and every gas atom pushes against the polar water molecules evenly, also causing the spherical shape of bubbles.
Extension - Water in Space (5-PS2.B)
- Without the force of gravity in space, the water forms a sphere (see above)
Extension - Water Ecosystems (5-EES2)
- 60% of the human body is water and 70% of the earth’s surface is water
- Water is one of the few substances that can exist in all three states of matter — solid, liquid, and gas — naturally on earth
- The water molecule’s polar characteristics allow it to have an important impact on life underwater and above water
- The hydrogen bonds between water molecules cause the solid form to be less dense than the liquid form, allowing ice to float
- This video from Ted-Ed has a great explanation, though it may be a little complex for 5th-grade https://youtu.be/UukRgqzk-KE
- If ice did not float, life underwater would not be possible. Every time a lake froze, it would freeze all the way, and all the fish and plant life underwater would freeze too.
- The hydrogen bonds between water molecules also cause water to have high specific heat capacity, meaning that water is resistant to changing temperatures
- This property of water is what helps regulate the Earth’s atmosphere and temperature, and influences climate.
- Notice that climates are much milder (there is less variation) in places near water than places (land-locked) that are not surrounded by water.
Extension - Internet/Article Credibility