Warm-Up: Can a paperclip float on water?
Prior to the class, place a clear plastic cup or beaker of water on each table. As students enter the class, inform them that cups of water are on their desks. Instruct them to exercise caution and not spill the water. Tell them that the purpose of the cups will be explained later.
Remind students to consider what they learned from the Properties of Water, part 1 lesson. Allow 2-4 students to respond. Require students to provide rationales for their responses. Give those who do not volunteer to answer the question an opportunity to participate by asking individual students if they agree or disagree with the opinion stated. Without leading students to the correct answer, listen and pay attention to note any misconceptions that arise in the responses from the class. Expect that many students will state that a paperclip cannot float on water, citing mass as the reason why the paperclip cannot float.
Inform students that they will now test whether a paperclip can or cannot float on water. Distribute one paperclip to each group of two students. Instruct students to work in pairs and tell them to attempt to float the paperclip on the surface of the water. Give students 3-4 minutes to try. Walk around the room to listen to students’ ideas for how to float the paperclip. When the 1st group is successful floating a paperclip, announce their success to the rest of the class. This will add validity to the idea that the paperclip can float. Allow other students to continue to try until the allotted time has passed. Once time ends, ask those students who were successful in floating the paperclip to share the process they used.
Instruct students to pour the water down the sink and place the paperclip on the desk. Note: It’s helpful to release students in small groups (e.g. “Tables 1 and 3, go to the sink.”) to perform an act like this. By instructing small groups of students to move instead of the entire class, students can quickly complete the task and not become engaged in off-task behavior or conversation.
Close by explaining that this activity demonstrated one of the properties of water, surface tension. Inform students that they will learn more properties of water in the lesson that follows.
This activity is a great way to start the lesson and “hook” students so expect reluctance to stop trying to float the paperclip. But, set a timed period for trying to float the clip and stick to it or run the risk of not getting to the instruction. Removing the water from the desks eliminates the distraction once instruction begins.
Introduce new vocabulary terms: covalent bonds, polar (polarity), density, adhesion, cohesion, capillary action, solution, solute, and solvent. Ask students, what does the prefix, “co” mean? Look for students to think about other words that use the prefix, “co”. Look for students to articulate that “co” means together. Refer back to the new terms, identify the terms that include the prefix “co”. Look for students to make the connection that covalent bonds means that bonds are “shared” or “together”. Instruct students to add cohesion to theirVocabulary Map, as is the practice for terms that contain prefixes, suffixes, Greek or Latin root words.
After introducing the new vocabulary, present key concepts related to the properties of water. Project key concepts on a LCD projector and distribute Guided notes for students to complete. Providing information verbally and visually helps meet the different learning styles.
Talk about the three states of water. Use the following visual activity to help students understand the difference between the three states of water. Select three students and inform them they are water molecules. Instruct the class to closely watch the “water molecules” and consider which state of water is being demonstrated by how the “molecules” move. Narrate the movement, while the “molecules” model each of the three states of water:
First, instruct the three water molecules (students) to walk around the room, far apart and separate from one another. Inform the students that they are free to also move outside the room. Tell students that the movement is random. Give students 5 seconds to watch the movement. Ask the class to consider the three states of water and decide what state of water is represented by this movement. Look for students to correctly identify that the movement represents the gaseous state. Ask them how they know that the movement represents the gas state. Look for students to identify that the molecules are far apart from one another and not confined to a space.
Second, take a piece of string or yarn and enclose all three water molecules (students) loosely in the string. Instruct the “molecules” to move as freely as they possibly can within the boundaries of the string. Tell them that they should bump gently into one another. Narrate to the class that the movement is still random but enclosed within the boundary of the string. Ask the class to consider the three states of water and decide what state of water is represented by this movement. Look for students to correctly identify that the movement represents the liquid state. Ask them how they know that the movement represents the liquid state. Look for students to identify the movement is within a confined space and that the “molecules” are bumping into one another.
Third, instruct the “water” molecules (students) to stop moving and stand side by side with the palms of their hands touching. Instruct the students to extend their arms and press away from one another, still with the palms of their hands touching. This will cause the string to break. Ask the class to consider the three states of water and decide what state of water is represented by this movement. Look for students to correctly identify that the movement represents the solid state. Ask them how they know that the movement represents the solid state. Look for students to identify that the molecules did not move and that the molecules expanded, forming a crystalline structure (as evidenced by the extended arms and touching palms) which caused the string to break.
Share the first 10 minutes of a video, Water's physical properties found on the Discovery Education site (a great teacher resource). Establish the expectations for viewing a video before beginning the clip. Tell students what you expect them know when the clip ends. Share a few questions before viewing. For example:
After the clip ends, allow students to respond to the questions that were posed before the video. Listen for students to be able to identify that water’s polar property allows it to combine with most substances, that water absorbs heat, and that convection currents hold heat near the bottom of a lake, while allowing the surface to freeze. Students should be able to explain that the frozen surface acts as an insulator, holding the heat at lower depths of the lake.
Distribute cards that show the parts of a writing strategy called RACE (re-state, answer, cite and explain). Display the writing strategy on a projector while explaining the parts of the strategy to address the needs of different learner types. Explain each of the four points that students should address when writing:
Re-state: Re-state the question and make it a part of your response.
Answer: Answer all parts of the question. Use sentence starters like, “I think” or “I believe”.
Cite: Cite evidence that supports your answer. Use your notes as a reference. Use sentence starters like, “The text says” or “The video showed…” or “For example…”
Explain: Explain how the evidence you cited supports your idea. Use sentence starters like, “This means...” or “This shows…”
Model how to respond to a writing prompt using the RACE strategy, using one of the questions posed to students while watching the video. The use of one of the previously asked questions should help students follow and focus the components of the RACE writing process rather than thinking about the answer to the question, given that the response has already been discussed.
Think aloud as you respond to each of the four components. Be sure to identify the part of the strategy that you are writing about and narrate the reasoning and thought process for each part of the response as you write. Use an LCD projector or whiteboard to show your written responses as you narrate. Distribute a RACE Constructed Response Grading Rubric to inform students about what is expected in the completed task.
The rubric not only serves to inform students, but it also guides the assessment of the work after it is collected and reviewed for a grade.
Explain that students should be able to write about things that they know about. Having learned about water, explain that they should be able to respond to a series of writing prompts on the properties of water.
Display four Constructed Response Writing Prompts. Distribute hard copies of the prompts, as well. Tell students that they should select and respond to 2-3 of the 4 prompts. Giving students a choice affords them a greater opportunity to experience success since they get to choose which questions they feel most equipped to respond.
Explain that the responses should include explanations that use the vocabulary that was discussed during the lesson. Make sure that students understand that responses that do not use any of the vocabulary of the concept do not meet the expectation for the task. Emphasize the importance of students using their notes to assist them with the task. Distribute a RACE constructed response rubric to inform students about what is expected in the completed task.
The three student work samples all demonstrate understanding of water properties, with differing degrees of specificity in the responses. The first and third responses are comparative as they both provide clear explanations for why a container will break if left in the freezer and why it is not safe to play on frozen lakes. However, neither include use academic vocabulary in the response, as instructed. The second student response provides accurate explanations and include appropriate use of academic vocabulary. This student also decided to respond to a third prompt and provide an explanation for why a belly flop in a pool is painful. Clearly, the second student response shows evidence of a greater depth of understanding than the first and third responses.
Distribute post-it notes. Instruct students to either write:
Explain that sunny means that the concept is clearly understood, partly cloudy means that there is some understanding but some parts of the concepts are not clear, stormy means that the concept is not understood at all.
Instruct students to place the post-it on the chart in one of the three categories as they exit class upon dismissal. Use the post-it responses, along with the student work to determine if the learning targets were met.