Photograph: Honey, R., Missoula, Montana, 2014
A. LEARNING OBJECTIVES
- Water takes care of us and it is important for us to take care of water.
- Experimentation, like mixing substances together, can sometimes cause a reaction and be fun and exciting.
- Water can have different properties, depending on what else is mixed with it.
B. LEARNING EPISODE DESCRIPTION
The Lewis and Clark journals on May 8, 1805 tell about a river that is the color of milk. The journals state, “… the water of this river possesses a peculiar whiteness, being about the color of a cup of tea with the a mixture of a tablespoonful of milk.” Lewis and Clark named it the Milk River (Lewis, Clark, and Members of the Corps of Discovery, 2002a). In September 1805, the Corps of Discovery reached a different river, which is now called the Clearwater River (Lewis, Clark, and Members of the Corps of Discovery, 2002b). Here, they met the Nez Perce tribe who call the river “Koos-Koos-Kia” because of how clear and transparent the water in this river appeared. The activities in this learning episode focus on the idea that water can have different properties that may or may not be healthy for us, or for other living beings. The main learning objective is that we need to take care of water (because water takes care of us) by making sure that our water is healthy and clean.
- Cabbage juice indicator: Cut up a whole red cabbage (it has to be the red variety) and boil the chunks in a large pot full of water until most of the red color is boiled out of the plant and the water is a bright purple color. Strain the cabbage out of the juice and put the cabbage juice into jars. For more directions, there are various videos online that demonstrate this.
- Small clear beakers or clear Dixie cups. Each child needs one beaker for each solution they are testing.
- Testing solutions: water and foods to make solutions with for pH testing.
- Crayons, markers, colored pencils (a range of colors to match the pH chart colors).
- pH color chart print outs for display and food pH chart print outs for each child to color in.
D. CIRCLE TIME
Ask the students, “Let’s talk about some ways that water helps us in our daily lives (drinking water, gardening, brushing teeth, washing clothes, etc.)?” Now ask the students “How do we know if our water is happy and healthy?” Revisit the discussion about where the water is in the community and refer to the map that your class created. Discuss where the water that you drink comes from. Ask the students if they think the water from the pond or the ditch is happy and healthy, and clean enough for them to drink? What do you think might happen to plants and animals (and to us?) if we drink water that is not clean? Ask students to practice saying some Nez Perce words like the name they called the Clearwater River, “Koos-Koos-Kia,” and the Nez Perce word for water, “Kús” (Native Languages of the Americas (2013). Have them repeat these back to you.
Ask students to draw a happy and healthy body of water in their journals, and then ask them to draw an unhappy or unhealthy body of water. Ask them to think about the discussion from circle time about happy and healthy water, and to name some things that might make our water not very happy and not very healthy? Ask them to draw these, or write the words onto the unhappy/unhealthy body of water in their discovery journal. Some examples might be garbage, chemicals, dirt, smoke, or poison. Invite them to do the same thing with the happy and healthy water. Examples of things that might make our water happy and healthy might be: vegetation by the water (swamps, marshes, and wetlands), recycle and throw away trash properly, don’t pour chemicals down sinks, use non-poisonous products. Some of these ideas may be difficult to represent in Discovery Journals. However, a discussion about these ideas can be important for the learners to think about how their actions can change the health of the water around them.
Books to Read
- Bull Trout’s Gift: A Salish Story About Reciprocity [Book 15] (Confederated Salish/Kootenai Tribes, 2011).
- Did a Dinosaur Drink This Water? [Book 16] (Wells, 2006).
- Book List
Learning about pH
Explain the following to your students: Healthy water has a pH of 7.0. But sometimes, different kinds of chemicals get mixed into lakes and rivers, and can get into the water that we drink. pH levels range from 0 to 14. If the pH of a solution is less than 7.0, the substance is an acid, if it is 7.0 it is neutral (water), and a solution with a pH higher than 7.0 is called a base. Since chemicals such as fertilizer or other pollutions can change the pH of something, testing it will tell us if it is healthy and happy water. You can read more about water pH at the U.S. Geological Survey (2013) site. This activity will familiarize learners with the idea that water can be just a little bit different, depending on what chemicals (and how many hydrogen molecules) are in it. This activity will familiarize students with the idea of testing water quality with a fun experiment that allows them to mix different colored solutions.
By using red cabbage juice as a pH indicator, students will test different foods, to begin to learn about the different pH of the foods that we eat. Red cabbage juice contains a mixture of colored substances that change from deep red at low pH to light blue at intermediate pH to yellow at high pH. Once students begin to understand that sugar, soda, juice, and even water from different locations can have different properties, this unit will help students to explore the idea that different things can change the pH of our water including pollution, animal excrement, pesticides, or even different kinds of soils being mixed into rivers or lakes.
- Mix solutions of various foods from the list below. Mixing the food with water to make a liquid makes a solution. Sometimes you need to squeeze or mash the food before mixing it with water.
|FOODS THAT CAN BE USED TO MAKE SOLUTIONS|
- Put each solution in a small clear plastic container (film canisters or clear plastic Dixie cups will work). Try to have a solution from each pH category, or at least a good range of basic to acidic examples.
- Place a range of food solutions in front of the students. If you can, give each student his or her own set of solutions. This allows for individual practice mixing chemical solutions. Also have markers or colored pencils that align with colors on the pH color chart like the one below (California State University San Bernardino, 2012). You can download the following chart
- First, ask students to smell (and taste as long as you are using only solutions that are edible. If there is even ONE solution that is not edible, I recommend that you DO NOT have the students taste any of them).
- Drop or squeeze (using squeeze bottles or eye droppers) the cabbage juice into the cups full of food solution until you see a color change. Model this for the students before they try it on their own.
- Discuss each color change with the children, and look up the pH level/color on the pH chart. Once you agree on a color, ask the students to color in the pH level on their food chart. You can create a food chart like the one that follows.
This activity is more advanced than some of the others in this curriculum. Emerging learners may need more assistance for this activity with their fine motor skills in mixing the solutions and deciding which color of pen the solution is the closest to. Though they may not fully comprehend the idea of measuring pH, this activity will still familiarize the students with the idea of experimenting and mixing, and that solutions that might look the same in the beginning have different reactions to the cabbage indicator.
Ask advanced learners to help the emerging learners with their experimenting and color matching. These students might be able to distinguish between what foods are healthier to eat, and where they fall on the pH scale. Ask the students, “What do you think would happen to the fish in the ocean or in the rivers, if the whole river were made out of soda, or sugar? Would that be healthy for the fish?”
Please be mindful of the students you are working with, and recognize that some of them might not have some of these foods available to eat in their homes. Try using foods that are not extravagant like lemon juice or tea. Or, have special snacks for them to eat that include some of the foods that you are testing. Also, if there are traditional foods available (e.g. tinpsila, huckleberries, bitterroot, camas, etc.) try making solutions with them and testing their ph. Talk about the foods that their ancestors ate, and what their pH levels are.
Happy and Healthy Water
This learning episode will give the children the opportunity to think about how clean the water is in their community. Read the following story.
- Plan a field trip with the children in order to collect samples of water from ponds, lakes, rivers, and streams or even from a mud puddle or a swimming pool.
- Have the children take part in this experiment by looking at the community map (from Learning Episode 1) with them and identifying locations to collect the samples from.
- Go to a location with water and help them collect some data water samples in jars. Be sure to label all of them.
- Bring the water samples back to your classroom, place small amounts of the sample in clear containers and test them with cabbage juice. Arrange them in order. Ask students to use the colored markers and record their conclusions in their discovery journals.
- Listen to the following recording of Dr. Shane Doyle, talking about how important water is to the Absaalooke Tribe. Talk about what it means to take care of water in your community. What does this mean?
- Have a discussion about how healthy the water is in your community. Remind them that the water in your community comes from other places, and that eventually it will travel away from your community and into other places in the world. Talk about the plants and animals that live in this water, and about how when water becomes more acidic, fish have trouble reproducing (having babies). When it becomes even more acidic, fish can die. Ask, “Do we notice different kinds of plants and animals that live in water that has different pH levels? How do you think the pH level of water might change the health of plants and animals? How does pH of water effect what lives in the water?”
F. SUGGESTED FORMATIVE ASSESSMENT
During snack time or at other times throughout the day, ask the students questions about the pH activity that you did together. Ask them why one solution turned bright pink, and the other solution turned green? They won’t be able to articulate very complex reasoning about this. However, at this point in their learning the students should begin to understand that solutions or foods are made up of different substances. Some of these substances are healthy for us and for the world, and some of them are not so healthy.
G. BIBLIOGRAPHY AND RESOURCES
California State University San Bernardino (2012) Chemistry in the Classroom, Retrieved from: http://chem.csusb.edu/studentInformation/chemClassroom.html
Carter, E., Green, S. and Taylor, J. (2003). NASA Native Earth System Science Curriculum Project Cleansing, Sparkling Koos, Nez Perce Reservation, Lapwai, Idaho.
Confederated Salish and Kootenai Tribes (2011) Bull Trout’s Gift: A Salish Story about the Value of Reciprocity. Lincoln, Nebraska: University of Nebraska Press.
Essence-of-Life (2012). A list of Acid/Alkaline Forming Foods. Retrieved from: http://rense.com/1.mpicons/acidalka.htm
Lewis, M., Clark, W., and Members of the Corps of Discovery. (2002a). May 8, 1805. In G. Moulton (Ed.), The Journals of the Lewis and Clark Expedition. Lincoln: University of Nebraska Press. Retrieved April 27, 2014, from the University of Nebraska Press / University of Nebraska-Lincoln Libraries-Electronic Text Center, The Journals of the Lewis and Clark Expedition website: http://lewisandclarkjournals.unl.edu/read/?_xmlsrc=1805-05-08.xml&_xslsrc=LCstyles.xsl
Lewis, M., Clark, W., and Members of the Corps of Discovery. (2002a). September 21, 1805. In G. Moulton (Ed.), The Journals of the Lewis and Clark Expedition. Lincoln: University of Nebraska Press. Retrieved April 27, 2014, from the University of Nebraska Press / University of Nebraska-Lincoln Libraries-Electronic Text Center, The Journals of the Lewis and Clark Expedition website: http://lewisandclarkjournals.unl.edu/read/?_xmlsrc=1805-09-21.xml&_xslsrc=LCstyles.xsl
U.S. Geological Survey (2013). Water properties: pH. Retrieved from: http://ga.water.usgs.gov/edu/ph.html
Wells, R. E. (2006). Did a Dinosaur Drink This Water? Park Ridge, Illinois: Albert Whitman and Company.