1. Teacher Guide
This lesson is designed to teach kids to ask a critical thinking question that you can’t just put into a search box to solve. To do that, we encourage them with smaller questions that search can help them answer. Make sure that you read the notes for each slide: they not only give you teaching tips but also provide answers and hints so you can help the kids if they are having trouble.
Remember, you can always send feedback to the Bing in the Classroom team at You can learn more about the program at bing.com/classroom and follow the daily lessons on our Partners In Learning site.
Want to extend today’s lesson? Consider using Skype in the Classroom to arrange for your class to chat with another class in today’s location. And if you are using Windows 8, you can also use the Bing apps to learn more about this location and topic; the Travel and News apps in particular make great teaching tools.
Nell Bang-Jensen is a teacher and theater artist living in Philadelphia, PA. Her passion for arts education has led her to a variety of roles including developing curriculum for Philadelphia Young Playwrights and teaching at numerous theaters and schools around the city. She works with playwrights from ages four to ninety on developing new work and is especially interested in alternative literacies and theater for social change. A graduate of Swarthmore College, she currently works in the Artistic Department of the Wilma Theater and, in addition to teaching, is a freelance actor and dramaturg. In 2011, Nell was named a Thomas J. Watson Fellow and spent her fellowship year traveling to seven countries studying how people get their names.
This lesson is designed to teach the Common Core State Standard: Reading: Informational Text
CCSS.ELA-Literacy.RI.3.3 Describe the relationship between a series of historical events, scientific ideas or concepts, or steps in technical procedures in a text, using language that pertains to time, sequence, and cause/effect.
CCSS.ELA-Literacy.RI.3.5 Use text features and search tools (e.g., key words, sidebars, hyperlinks) to locate information relevant to a given topic efficiently.
CCSS.ELA-Literacy.RI.3.7 Use information gained from illustrations (e.g., maps, photographs) and the words in a text to demonstrate understanding of the text (e.g., where, when, why, and how key events occur).
CCSS.ELA-Literacy.RI.3.9 Compare and contrast the most important points and key details presented in two texts on the same topic.

2. How does the process of evaporation create salt that’s ready to be harvested?
© Art Wolfe/Mint Images
Having this up as kids come in is a great settle down activity. You can start class by asking them for thoughts about the picture or about ideas on how they could solve the question of the day.

3. How does the process of evaporation create salt that’s ready to be harvested?
In the southernmost reaches of San Francisco Bay, salt is still harvested from 150-year old evaporation ponds. The red tint to the water may look like industrial waste, but the color comes from increased mineral concentration and bacteria growth as the water evaporates, leaving behind salt to harvest for commercial sales.
Much of the bay was cordoned off and transformed into salt evaporation ponds from the mid-1800s to the early 20th century. The result of that unchecked alteration meant the loss of many acres of salt marshes and natural wetlands that supported San Francisco Bay’s diverse wildlife. In the past several years, however, a growing effort to restore the health of the bay’s ecosystem has reclaimed many of the filled-in marshes and returned them to their previous natural state.
Depending on time, you can either have students read this silently to themselves, have one of them read out loud, or read it out loud yourself.

4. How does the process of evaporation create salt that’s ready to be harvested?1
Image Search
Find a diagram online that shows you the process of evaporation. What happens to water in this process and where does it go? 2
Video Search
Find a video online that shows you the process of evaporation. What happens to water in this process and where does it go? 3
Web Search
Read online about the process of evaporation. What happens to water in this process and where does it go? 4
Map Search
Find San Francisco on a map of the United States. Why might it be a good location for salt water evaporation? 5
What do the different colors in the evaporation ponds indicate? How might this help people know when salt is ready to be harvested?
There are a couple of ways to use this slide, depending on how much technology you have in your classroom. You can have students find answers on their own, divide them into teams to have them do all the questions competitively, or have each team find the answer to a different question and then come back together. If you’re doing teams, it is often wise to assign them roles (one person typing, one person who is in charge of sharing back the answer, etc.)

5. How does the process of evaporation create salt that’s ready to be harvested?5
Minutes
You can adjust this based on how much time you want to give kids. If a group isn’t able to answer in 5 minutes, you can give them the opportunity to update at the end of class or extend time.

6. How does the process of evaporation create salt that’s ready to be harvested?1
Image Search
Find a diagram online that shows you the process of evaporation. What happens to water in this process and where does it go? 2
Video Search
Find a video online that shows you the process of evaporation. What happens to water in this process and where does it go? 3
Web Search
Read online about the process of evaporation. What happens to water in this process and where does it go? 4
Map Search
Find San Francisco on a map of the United States. Why might it be a good location for salt water evaporation? 5
What do the different colors in the evaporation ponds indicate? How might this help people know when salt is ready to be harvested?
You can ask the students verbally or let one of them come up and insert the answer or show how they got it. This way, you also have a record that you can keep as a class and share with parents, others.

7. How does the process of evaporation create salt that’s ready to be harvested?1
Image Search
Find a diagram online that shows you the process of evaporation. What happens to water in this process and where does it go?
(Possible queries: “Bing/Images: evaporation diagram”, “Bing/Images: process of evaporation”).
Answers will vary. Students should find an age-appropriate image that shows them the process of evaporation. For example, the diagram found here: After studying the image and captions, students should be able to answer that in the process of evaporation, liquid water dries up and goes into the air, eventually helping to form clouds.

8. How does the process of evaporation create salt that’s ready to be harvested?2
Video Search
Find a video online that shows you the process of evaporation. What happens to water in this process and where does it go?
(Possible queries: “Bing/Videos: for kids, understanding evaporation”, “Bing/Videos: for kids, process of evaporation”).
Answers will vary. Students should watch a video (such as the one found here: to see how the process of evaporation works. In this video, a drying coat is used as an example to explain how water transforms from liquid form to gaseous form. After watching, students should understand that evaporation is when water dries up and disappears into the air (with the sun and wind as major contributors to this process).

9. How does the process of evaporation create salt that’s ready to be harvested?3
Web Search
Read online about the process of evaporation. What happens to water in this process and where does it go?
(Possible queries: “understanding evaporation for kids”, “for kids, what is evaporation?”).
From
Evaporation occurs when a liquid changes its state to form a gas or vapor. Most that occurs on Earth is the change from the liquid state of water to a water vapor. Though it looks very simple, water is not only the most abundant compound on Earth, it is also very complex. The quantity of water on the Earth never changes; it simply changes form as it passes through what is known as the water cycle.
From this description, students should understand that in the process of evaporation, water changes from a liquid into a gas or vapor in the air.

10. How does the process of evaporation create salt that’s ready to be harvested?4
Map Search
Find San Francisco on a map of the United States. Why might it be a good location for salt water evaporation?
(Possible queries: “Bing/Maps: San Francisco”, “Bing/Maps: San Francisco, California”).
For example:
Students should look at San Francisco on a map and think critically about why it is a good location for salt water evaporation. In particular, encourage them to think about the bodies of water surrounding it. They should note that not only is the San Francisco Bay on one side of the city, but it borders the Pacific Ocean (full of salt water!) on the west.

11. How does the process of evaporation create salt that’s ready to be harvested?5
Web Search
What do the different colors in the evaporation ponds indicate? How might this help people know when salt is ready to be harvested?
(Possible queries: “how salt water evaporation ponds work”, “color of salt evaporation ponds”).
From
Due to variable algal concentrations, vivid colors – from pale green to bright red – are created in the evaporation ponds. The color indicates the salinity of the ponds. Microorganisms change their hues as the salinity of the pond increases. In low- to mid-salinity ponds, green algae such as Dunaliella salina are predominant, although these algae can also take on an orange hue. In middle- to high-salinity ponds, Halobacteria, which is actually a group of halophilic Archaea (sometimes called Haloarchea), shift the colour to pink, red and orange. Other bacteria such as Stichococcus also contribute tints.
In other words, the different colors in the evaporation ponds indicate different levels of salinity (or salt content). The color of the pond would help people know how much of the pond is salt and how much is water, showing how much water has already been evaporated into the air and when the salt crystals may be ready to be harvested.

12. How does the process of evaporation create salt that’s ready to be harvested?
This slide is a chance to summarize the information from the previous slides to build your final answer to the question. Students should use an understanding of the process of evaporation to explain how saltwater from the Pacific Ocean comes into these ponds in San Francisco. The sun and wind help the water evaporate from its liquid form into a gas, leaving salt crystals behind that are able to be harvested.