Lesson Plan Template s44
Lesson Plan: Properties of Water
Topic: The Properties of Water Date: Not sure yet (sometime in the week of Feb 7-11)
NSES: Grade level: 10th Grade
Teaching Standard B: Teachers of science guide and facilitate learning. In doing this, teachers
· Focus and support inquiries while interacting with students.
· Orchestrate discourse among students about scientific ideas.
· Encourage and model the skills of scientific inquiry, as well as the curiosity, openness to new ideas and data, and skepticism that characterize science
The properties of water are not well represented in the NSES Life Science content standard (i.e., Content Standard C). That said, the following standard is loosely related to water properties:
Content Standard C4: The Interdependence of Organisms
“The atoms and molecules on the earth cycle among the living and nonliving components of the biosphere.”
SOL:
BIO.3 The student will investigate and understand the chemical and biochemical principles essential for life. Key concepts include
a) water chemistry and its impact on life processes
Subject: Advanced Biology
Daily Question: How do the properties of water help it to support life?
Procedures for Learning Experience / Guiding Questions / Materials Needed / Evaluation (Assessment) / Approximate Time NeededEngagement:
I will write the following questions up on the board, and the students will be asked to answer them on a blank sheet of paper
1)
a. Human brains are ____% water.
b. Human bones are _____% water.
c. Human blood is ____% water.
2) How long can a person live without water?
3) ____% of the Earth is covered in water.
I will then show the answers, ask if the students are surprised by any of the answers, and ask why. / 1) How important is water to humans? / Whiteboard / This activity will serve as a pre-assessment to gauge students’ prior knowledge about the importance of water. / 10 minutes
Exploration:
Students will complete an inquiry activity—the Penny Lab—to introduce them to the concept of surface tension/cohesion. In this activity, students will be asked to hypothesize how many water drops they can fit on the surface of a penny. They will then use eye droppers to test their hypothesis and will be asked to make qualitative observations about the water surface as more drops are added.
Explicit connections to the nature of science will be made after the activity, when I will ask the students why we did multiple trials of the experiment. We will also discuss how the non-soapy pennies represent the control group and the soapy pennies represent the experimental group
Once the students have completed the first part of the activity, they will dip their penny in soap and again test to see how many water drops they can fit on their penny. They will be asked to hypothesize whether the number of drops will increase, decrease, or stay the same. Again, they will be asked to make qualitative observations about the water surface and note any changes from the “Water Only” trials.
In the results section, they will be asked to report the number of drops for the soapy penny and take a guess, based on their observations, as to why they could not fit as many water drops on the soapy penny. / 1) How many drops of water can we fit on the surface of a penny?
2) How many drops can we fit on the surface of a soapy penny? Is it more drops, less drops, or the same number of drops as we fit on the non-soapy penny?
3) What do you notice about the water surface as more drops are added to the soapy vs. non-soapy penny?
4) How does soap affect the attractive forces between water molecules? (Note: I will not actually ask this question during the Exploration Phase, but it will be addressed at the beginning of the Explanation phase) / Pennies (one per pair of students), Eye droppers, Soap, Penny Lab worksheets / Each student will fill out the Penny Lab worksheet, which will be turned in to me after the activity. I will also walk around and ask Guiding Question #3 of various lab groups to check student comprehension/ progress. / 20 minutes
Explanation:
At the beginning of this phase, we will discuss the results of the Penny Lab, and the students will be asked to share their guesses as to why fewer drops fit on the soapy penny.
The teacher will then explain that the soap lessens the attractive forces between water molecules. The students will be asked to share their observations of the appearance of the water surface on the non-soapy penny. They will most likely describe it as a “bubble,” which I will explain results from cohesive forces between the molecules that give water a particularly high surface tension.
We will define the terms cohesion and adhesion, and the students will watch a video about the water strider bug, which is able to “walk on water” due to the high surface tension of water and unique anatomical adaptations. The video can be found at the following URL:
http://www.youtube.com/watch?v=RphuMEUY3Og
After the video, I will ask the students questions #3 and #4, and we will launch into an explanation of why water has such strong attractive forces—its polarity!
To illustrate the polar nature of the water molecule, I will show a diagram of the water molecule that illustrates covalent bonds between hydrogen and oxygen. I will then have three student volunteers come up to the front of the room. The tallest volunteer will be the oxygen atom and the shorter volunteers will be the hydrogen atoms. Apples (or some type of round food item) will represent shared electrons, and the oxygen volunteer will be told that he is particularly “hungry” that day. He will pull the apples closer to him, and we will discuss how he has a stronger negative charge than the hydrogen atoms b/c the electrons are now closer to him. This makes the water molecule “polar” and allows for attraction between water molecules (hydrogen bonds), which gives water its unique cohesive properties.
We will also discuss how water is also adhesive due to hydrogen bonding, and how cohesion and adhesion relate to transpirational pull in plants. The following animation will help illustrate transpirational pull as it relates to water properties http://academic.kellogg.edu/herbrandsonc
/bio111/animations/0031.swf . We will go through the animation step by step.
After this, I will ask students if ice floats or sinks and ask them if this is contrary to what they would expect. We will then discuss how water has a higher density in its solid form (ice) than its liquid and gas forms due to the arrangement of hydrogen bonds. I will use two animations at the following URL http://www.visionlearning.com/library/
module_viewer.php?mid=57 to better show hydrogen bond formation in water’s liquid vs. solid states.
To illustrate the solvent properties of water, I will use the interactive features of the Promethean board. I will ask students to come up and draw water molecules surrounding Na + and Cl – atoms (table salt). We will then view the following animation to better visualize the process of salt dissolving in water.
http://www.chem.iastate.edu/group/Greenbowe/sections
/projectfolder/flashfiles/thermochem/solutionSalt.html
After this, will discuss the pH of water, as it relates to that of acids and bases.
Finally, I will explain how water has a high specific heat due to the attraction between molecules. To illustrate the significance of this, we will discuss lake effect cooling/warming. / 1) What are the unique properties of water?
2) How does the structure of a water molecule account for these unique properties?
Examples of specific questions to be asked during class:
3) Summarize why a water strider is able to walk on water.
4) Could humans ever walk on water? How are we different from a water strider? / Promethean board, teacher computer, projector, 4 apples / During the apple demo and promethean board demo, I will be interacting with the volunteer students and will be able to assess their comprehension directly. Also, I plan to ask questions throughout the explanation phase to check the students’ understanding. / 45 minutes
Extension:
The students will be presented with a scenario about a fictional lake (Lake Ottolini) that is teeming with animal and plant life. They will be asked to predict what will happen to life in the lake when a tricky alien population that wants to take over Earth decides to lower the specific heat of water.
The students will be asked to work on the activity with the person sitting next to them, and we will discuss as a class after 10 minutes.
At the end of the class period, I will show a summary slide listing the properties of water that we discussed during the lesson: polarity, cohesion, adhesion, lower density as a solid than a liquid, high specific heat, good solvent, neutral pH
Note: Due to time constraints, I may need to assign the activity for homework and have the class discussion the next day. / 1) What would happen to lake organisms if we lowered the specific heat of water?
2) Would the organisms be able to survive? Why or why not. / “Aliens HATE Lake Ottolini” worksheet (one per student) / I will collect the “Aliens HATE Lake Ottolini” worksheet to assess students’ ability to apply their knowledge of specific heat to a novel situation. / 15 minutes
Notes:
1) Connection to other lessons: This lesson is designed to be incorporated into a week of lessons concerning biochemistry. Understanding the polarity of water will help students to understand polarity in biological molecules. Additionally, the extension phase of this lesson hits on a key concept of ecology—the idea that organisms interact with the abiotic and biotic components of their environments.
2) Safety Notes: There are no major safety considerations for this lab, though students will be instructed not to throw their pennies.
3) Differentiation: During the Exploration Phase and Extension Phase, I will be able to circulate around the room and provide some individualized assistance. This is particularly important during the Extension Phase, as the scenario posed is a bit abstract, and some students may benefit from increased scaffolding.
4) Technology Component: The three animations in this activity, which are used to demonstrate hydrogen bonding, transpirational pull, and water’s solvent properties, are included in the Extension Phase. These animations support the instruction in that they help students to visualize key processes/properties in a way that is not possible with pictures alone. Additionally, the interactive features of the Promethean board will be used such that students can further explore the process of table salt dissolving in water.