2. Balance: Sinking and Floating

(This is the Lesson Plan 2 for Rose Honey’s curriculum, Discovering Our Relationship with Water.)


Photograph: Honey, R., 2014


  • Water has relationships with entities in the world.
  • The relationship between objects and water will determine whether an object floats or sinks.
  • Objects are made out of different kinds of materials.
  • We can predict whether an object will sink or float based on its properties.
  • We can test our predictions by experimenting, make conclusions based on the experiments that we do, and apply what we have learned to different situations.


Near the end of August in 1804, Lewis and Clark met with the Yankton Dakota Sioux Tribe (Ihanktonwan Dakota Oyate) near a place that Lewis and Clark called Calamut Bluff. At this location, one of their boats hit a snag in the river, causing it to have a hole and almost sink to the bottom of the river. You can read about this in Clark’s journal on August 28th, 1804 (Lewis, Clark, and Members of the Corps of Discovery, 2002a). You can utilize this story to introduce the idea that along their journey, Lewis and Clark had to make sure that their boats were able to float in order to transport them down the river. Introduce this idea to your early learners by saying things like, “What makes a boat float? What do you think happens to a floating boat that might make it sink? What kinds of materials are boats made of?”

This unit is focused on balance and the importance of having a balanced relationship with water. From experiences in the bathtub, in swimming pools, or at the beach, young learners form early ideas about sinking and floating and tend to focus on the properties of the object instead of the relationship between the object and the liquid. Even the words “sink” and “float” indicate that an object has a property within it, which results in it being a “sinking” object or a “floating” object. But an object only sinks if its density is higher than the liquid it is submersed in, and only floats if its density is lower than the liquid it is placed in. From a scientific perspective, objects float when the upward push of water balances the downward push of the object. Objects sink when the downward push of the object is greater than the upward push of the water (Department of Education and Early Childhood Development, 2013). Though preschool children may not yet be able to grasp the complexity of this concept, this learning episode introduces the idea of balance. Instead of focusing on whether objects sink or float in water, this unit is designed to inspire learners to think instead about the balance between objects and the liquid they are immersed in.


  • Large bucket or container (clear if possible) big enough to fit two cans of coke
  • 1 can of regular Coke and 1 can of Diet Coke
  • Objects such as a sponge, paper clip, toothpick, marble, straw, crayon, leaf, twig, bark, rock, fruit, etc.
  • Butcher paper, markers
  • Water table or large bins of water for multiple children to experiment with objects and water balance.


Let your learners know that today you are going to explore relationships between different objects and water. Before talking about sinking/floating, demonstrate objects that have a balanced relationship with water. Show the students a bucket of water, a diet coke, and a regular coke. Drop the cans of coke into the bucket of water and ask the students: What do you observe (see)? What do you notice? Lead the conversation towards the idea that sinking and floating is about the balance between objects pushing down on water, and water pushing up on the object (not property of individual items). What kind of relationship does the diet coke have with the water – is it balanced? What relationship does regular coke have with the water – is it balanced? Then ask the students – What kind of relationship do you have with water? Tell your students that the Dakota word for water is “mini” [mee nee] (Native Languages of the Americas (2013). Have them repeat this back to you.

Discovery Journals

Ask the students to draw pictures of things that they have seen when they have visited water. Give them some prompts such as, “Name some things that you see when you go to the lake river/ocean. Which of those things are on top of the water? Are any of them under the water? What happens to the soap when you take a bath? What about when you go swimming?” Ask students to share their experiences with water to the group.


Listen to the audio of Renee Sans Souci talking about her relationship with water

as an Omaha woman. After listening to this story, ask the students if they can remember what the Omaha word is for water (“ni” [nee]). How is this the same or different from the Dakota word for water?

Books to Read

  • Shin-chi’s Canoe [Book 3] (Campbell, 2008)
  • Morning on the Lake [Book 4] (Waboose, 1998)
  • Skokomish Baskets and Canoes [Book 5] (Coast Area Planning Committee, 1978)
  • Book List



0688e706cb13fd4bb7e9e1efa915964eInside Activity

 Density Relationships

  • Introduce a number of objects into the discussion circle (small sponge, paper clip, buttons, toothpick, marble, plastic straw, crayon, leaf, twig, piece of bark, rock, pieces of fruit, etc.) and ask the students to “predict” the relationship the objects have with water. Tell them, “Let’s make a hypothesis about what will happen when I drop this object into a bucket of water.” Use questions like, “Will the ‘up’ push of water balance the ‘down’ push of the object?” Then talk about testing your prediction and experiment by immersing the object into a bucket of water or water table.
  • Tape a large piece of paper on the wall and record student predictions for each object in a table. A prediction is a guess about what might happen based on observation. For example PDF: Object/Water Relationship Table
  • Have students explore and test the objects in bins of water. Model how to record your data by filling in the chart when each child makes a new discovery.

Emerging Learners

Learners in the earlier stages of cognitive development will be able to think about objects in terms of color and shape (Informed Parents Successful Children, 2008). Ask these students if objects of different colors and shapes go to the bottom of the water bucket, or float in the water. For example, “Does the red button go to the bottom or stay on top? What about the blue button? Do both the red and the blue button act the same when you place them in the bucket, or do they act differently? What about the round wooden block? Does it act the same or different from the way that the square wooden block acts when we put it into the bucket of water?”

Advanced Learners

Learners who are more advanced can think about how “heavy” or “light” and object is. Remember to talk about the relationship between the object and the water. Ask them questions like, “Which one do you think is more dense? Does the rock have a larger density, or does the water have a larger density? Let’s put the rock into the water and find out. Oh! The rock goes to the bottom, so the rock has a greater density than the water. This means that the down force of the rock pushing on the water is larger than the up force of the water pushing on the rock. Now let’s try this feather! Do you think that the feather will have a bigger down force, or the water will have a bigger up force? Does this mean that the feather will go to the bottom, or stay on top?”

Helpful Hints

Do not “dumb down” words or concepts when working with the children. In this learning episode, I encourage use of the word “density” and “force” to explain the properties of the objects the students are experimenting with. Using the proper words will familiarize early learners with this language, and promote thinking about things from a scientific perspective.


fb65735a70bf1412e670c3edcde3911bOutside Activity

Boat Building With Objects in Nature

Research Question

How can we build a boat that floats?

  • During circle time, ask the students: What do you think a boat needs in order to float? Look at the chart that you made during the object/water balance experiment. Let’s look at the data that the class collected together. How can our conclusions help us to answer our research question?
  • Show students pictures of different types of canoes and boats. Include pictures of Native American boats and the boats utilized by Lewis and Clark and the Corps of Discovery. Some examples of traditional Native American boats can be seen here. Ask the students to observe what these boats are made out of, and what shapes the boats are.
  • Tell the students: Let’s pretend that we need to help Lewis and Clark to build a new boat. How should we do this? What kinds of materials should we use? Encourage the students to think about all of the data you have gathered including your object chart, materials and shapes discussion from the photographs.
  • Go on an outing with the children to find items in nature to help them make boats. Remind students to think about the information that they know about boats from the observations and experimenting they have done.
  • Once you have collected materials, return to your classroom and begin building boats (you may want to gather extra materials from the forest for children who need more leaves, twigs, moss, etc.). Avoid telling children how to build a boat. Let them create their own designs – however improbable or silly. If you want, it is a good idea to guide by example. Participate as a peer, quietly making your own simple boat.
  • When the boats are finished, try floating them. Watch what happens and encourage students to talk about their boat design, describe the materials they used and to analyze with the children why some models work better than others. Can the children use the findings from these experiments to design their next boat?

Helpful Hints

Misconceptions that students can have about sinking and floating include: small objects float and large objects sink, soft objects float and hard objects sink, floating objects have air in them somewhere, floating means that most of the object is on top of the water, objects that are submerged (like fish or submarines) are not floating, and that floating has to do with the weight of an object. Ways to counteract these misconceptions or prevent them from developing in the first place include getting students to experiment and test different ideas and different objects and their relationship to water (English, Davies & Green, 2010).



  • Look at the chart that you created in the sink/float activity. Ask students to count the number of objects they tested that have a balanced relationship with water. How many objects did NOT?
  • During snack time or while traveling on field trips, ask students randomly whether they think this object (pick up a rock or a stick, for example) has a balanced relationship with water and to describe what might happen if you placed it in a bucket of water.
  • Discuss with students why they chose the materials and shapes they did when they built their boats, and ask them if they were to build a boat again, would they change anything?


Bullboat [Photograph]. (1860). Retrieved February 25, 2014, from: http://amhistory.si.edu/onthewater/exhibition/4_4.html

Campbell, N.I. (2008) Shin-chi’s Canoe. Toronto, Ontario: Groundwood Books. Coast Area Planning Committee (1978). Skokomish Baskets and Canoes, Coast Area Planning Committee. Retrieved from: http://apps.educationnorthwest.org/indianreading/4/book20.pdf

Curtis, E. (Photographer). (1910a). Home of the Kalispel [Photograph #28], Retrieved Sept. 18, 2013, from: http://blogs.denverpost.com/captured/2010/11/15/north-american-indian-photographs-by-edwardcurtis/2551/

Curtis, E. (Photographer). (1910b). Into the shadow—Clayoquot [Photograph #95], Retrieved Sept. 18, 2013, from: http://blogs.denverpost.com/captured/2010/11/15/north-american-indian-photographs-byedward-curtis/2551/

Curtis, E. (Photographer). (1910c). Canoeing on Clayoquot Sound [Photograph #94], Retrieved Sept. 18, 2013, from: http://blogs.denverpost.com/captured/2010/11/15/north-american-indian-photographs-byedward-curtis/2551/

Curtis, E. (Photographer). (1908). Mandan Bullboat [Photograph], Retrieved April 25, 2014, from: http://amhistory.si.edu/onthewater/exhibition/4_4.html

Department of Education and Early Childhood Development (2013). Floating and Sinking. Retrieved from: http://www.education.vic.gov.au/school/teachers/teachingresources/discipline/science/continuum/pages/floatsink.aspx

English, J., Davies, M., & Green, R. (2010). Floating and Sinking Rich Task. Retrieved from: http://learnonline.canberra.edu.au/portfolio/view/view.php?id=750

Informed Parents Successful Children (2008). Understanding and Supporting Your Child’s Development Age 3-5 Years. Retrieved from: http://www.marylandpublicschools.org/NR/rdonlyres/676DD433-449C-4A26-B364-0936353CBE4E/24408/IPSC_eng_35.pdf

Lewis, M., Clark, W., and Members of the Corps of Discovery. (2002a). August 28, 1804. In G. Moulton (Ed.), The Journals of the Lewis and Clark Expedition. Lincoln: University of Nebraska Press. Retrieved April 25, 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=1806-02-01.xml

Lewis, M., Clark, W., and Members of the Corps of Discovery. (2002b). February 1, 1806. In G. Moulton (Ed.), The Journals of the Lewis and Clark Expedition. Lincoln: University of Nebraska Press. Retrieved April 25, 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=1806-02-01.xml

Native Languages of the Americas (2013). Vocabulary Words in Native American Languages: Dakota Sioux.

Retrieved from: http://www.native-languages.org/dakota_words.htm

Waboose, J.B. (1997) Morning on the Lake. Toronto, Ontario: Kids Can Press.