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Daily Do

Why does ice melt without getting hotter?

Chemistry Crosscutting Concepts Earth & Space Science Is Lesson Plan NGSS Phenomena Physical Science Science and Engineering Practices Three-Dimensional Learning Middle School High School Grades 6-8 Grades 9-12

Welcome to NSTA's Daily Do

Teachers and families across the country are facing a new reality of providing opportunities for students to do science through distance and home learning. The Daily Do is one of the ways NSTA is supporting teachers and families with this endeavor. Each weekday, NSTA will share a sensemaking task teachers and families can use to engage their students in authentic, relevant science learning. We encourage families to make time for family science learning (science is a social process!) and are dedicated to helping students and their families find balance between learning science and the day-to-day responsibilities they have to stay healthy and safe.

Interested in learning about other ways NSTA is supporting teachers and families? Visit the NSTA homepage.

What is sensemaking?

Sensemaking is actively trying to figure out how the world works (science) or how to design solutions to problems (engineering). Students do science and engineering through the science and engineering practices. Engaging in these practices necessitates students be part of a learning community to be able to share ideas, evaluate competing ideas, give and receive critique, and reach consensus. Whether this community of learners is made up of classmates or family members, students and adults build and refine science and engineering knowledge together.

Introduction

Today's task asks the question, "Why does ice melt without getting hot?" This more fitting question might be, "Why does the temperature stay the same when water is melting and boiling?" (But it wouldn't fit in the space allotted.) This is the phenomenon students actively try to make sense of by engaging in multiple elements of developing and using models and using the thinking tools of patterns and the flow of energy and matter. The goal is for students to begin to develop a deep conceptual understanding of the polar property of water molecules and how this property affects phase changes.

Set up Heating curve

Experience the Phenomenon

Tell students you have a puzzling phenomenon to show them! Ask students to create a space in their science notebooks to record noticings and questions that come up as they observe the phenomenon.

Show students data (graph) collected from heating ice water until it boils. You can share the graph above which is a snapshot from a video students watch later in the task or *collect and graph your own data to share. You might refer students to the set-up and note two things: (1) the hotplate heat setting was set to "4", and (2) the water was continuously stirred while the water was being heated.

*Analyzing data supports students' sensemaking. It is not necessary students conduct the investigation and collect the data themselves.

Ask students, "What patterns do you observe in the data presented in the graph?" Give students a few minutes to observe the graph and record their ideas before sharing them with a partner. As you move around the room and listen to students sharing ideas, you might ask:

  • What does the x-axis represent? The y-axis?
  • How is temperature changing over time?
  • How is rate of change(s) changing over time?
  • Can you quantify the patterns you are describing?

Also remind students to write down questions that arise while observing and identifying patterns in the data.

Bring the class back together and ask them to share the patterns they observed. Students will likely say:

  • The temperature increased from 0 C to 101 C
  • The temperature stayed the same twice; 0 C for about 150 seconds and 99-101 C for about 250 seconds
  • The line is flat, then steep, then flat again
  • The temperature stayed the same, increased fast, then stayed the same again

Say to students, "I've marked three locations on the graph, A, B and C. Can you create a model to explain the patterns in the temperature data you've observed?" Ask students to work in the alone zone (independent thinking time) to create their initial models. As you move around the room, you might ask questions to support students in creating their models:

  • What are the components of the system? (What are the parts of the system? What are the boundaries of the system?)
  • What energy is entering, staying, and leaving the system?
  • What forms of energy are involved in this system?
  • What happens to matter as it moves within/leaves this system?

Tell students to set their models aside (without sharing); we will come back to them.

Labeled heating curve

Heating Curve of Water

Tell students you have a video that shows the ice water being heated to boiling. Ask students to open their science notebooks and again record their observations and any questions that come to mind. Play the heating curve video (above).

Ask students to return to their models. Based on their observations, is there anything they would add to or change? Give students independent thinking time to revise their models. Next, ask students to share their models with a partner or small group. You might use the following partner conversational supports to help facilitate their discussion:

Speaker: I added/changed ________ because _______.

Responder: I hear you say ______. I agree/disagree because _______. OR What evidence is that based on?

Make sure students have opportunities to switch roles.

Assign partners to small groups of four. Ask each group to create a group consensus model to explain the patterns in temperature data they've observed. As you move around the room, you might asks groups some of the same questions you asked to support students in creating initial models.

Create a classroom or virtual space for groups to share their consensus models. Ask students to visit at least three group models and at each model

  • record similarities and differences between their group model and the other group's model in their science notebooks;
  • post (using a sticky note or comment) one thing the other group's model does well (included a component their group didn't include, clearly conveys an interaction, etc.);
  • post one clarifying question to help the other group improve their model.

Give student groups an opportunity to revise their models based on peer-feedback and their observations of other group models. You might at this point choose to create a class consensus model. Begin by asking groups to share similarities between the models; ask students how you should represent the components and interactions on on the class model. Suggest noting places on the model the class is unsure of with question marks.

Ask students to review the questions they recorded in their science notebooks and add any new wonderings. Then, instruct students to share their questions with their group. Ask groups to choose two common questions and one question that was less common but feel the answer will help explain the phenomenon. Ask the groups to share these questions with the class. Student questions might include:

  • Do all substances produce the same shape (pattern in temperature data) when heated until boiling?
  • Does the amount of water (ice) in the beaker matter?
  • Does the amount of heat added matter? (What if you turned the temperature on the hot plate higher?)
  • What happens if you don't stir the water?
  • Can't ice be colder than zero?
  • Can't ice melt when it is colder than zero?
  • Can water keep getting hotter and hotter after it is a gas?
  • How would you measure the temperature of water gas/vapor?

You might say to students, "Many of us are wondering if we can change the shape of the line by increasing the hot plate's temperature. Should we investigate this questions first?"

NSTA Collection of Resources for Today's Daily Do

NSTA has created a Why does ice melt without getting hotter? collection of resources to support teachers and families using this task. If you're an NSTA member, you can add this collection to your library by clicking Add to my library (near top of page).

Check Out Previous Daily Dos from NSTA

The NSTA Daily Do is an open educational resource (OER) and can be used by educators and families providing students distance and home science learning. Access the entire collection of NSTA Daily Dos.

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