Storyline Link

1. Bring the students to a central area and have them guide you in drawing a picture on chart paper what the students recall doing to remove the crayon markings in Lesson 3: Different Properties for Different Purposes. Be sure to label and clarify students’ current thinking and wonderings. Any student questions should be added to the 2.1.C1: Student Question Chart.
2. Show students the anchoring phenomenon: Materials are made of matter. We can observe misshapen objects, including a crayon, lip balm, and a candle. Ask students to think-pairshare a response to this question: “Thinking about what you learned about solids and liquids, what can you now say about the properties of these misshapen objects?” ESRs: The crayon and the birthday candles are solids, and somehow they got spread out. The lip balm is also a solid, and when it got spread out it became squishy, but it’s not a liquid. None of them are liquids because I can’t pour them like the other liquids.
3. Ask students to think-pair-share a response to this question: “What else have you learned about the properties of liquids and solids?” ESRs: Last time, we used different solid materials to get the crayon marks off the cup. The kids in the stories used different solid materials to build things like a bridge. Maybe the crayon, the birthday candle, and the lip balm were once liquids.
4. Ask students to think-pair-share a response to this question: “We learned about the purpose of some materials. What is the purpose of the crayon, candle, and lip balm?” ESRs: The crayons are used to draw and color; the candle is used for a birthday cake; and the lip balm is used for our chapped lips.
5. Ask students to think-pair-share a response to this question: “Will the objects still work as they’re supposed to even though they’re misshapen?” ESRs: The crayons will kind of draw and color; the candle can probably be lit on a birthday cake but it won’t look nice; and the lip balm will be hard to put on because it will smear on my face. They work better when they’re just the regular way.
6. Ask students, “Have we figured out how these objects got misshapen?” ESRs: We already hit them, rolled over them, smashed, and nothing worked to make them look like they do now. I think they melted!
7. Ask students to think about how the misshapen objects changed and how this is similar or different from other changes we see around us. Tell students that now we will explore some other types of matter that we can change in different ways.

8. Distribute an unpopped corn kernel to each student. Have students make observations of the properties of the unpopped corn kernels. Have students share their observations. Chart student responses. ESRs: It is a solid. It is hard, smooth, “pointy” and brown. It is not a liquid.
9. Ask students to place the unpopped kernels in the air popper. Pop the kernels. Have students carefully observe what is happening to the kernels when heat is added.
10. Distribute a popped corn kernel to each student. Have students make observations of the properties of the popped corn kernel, and chart their responses. Students compare kernels before and after being heated. Have students think-pair-share observations. ESRs: It is hot. It got spread out. It is fluffy and white. It feels softer and crunchy. The kernel changed from hard and smooth to white and fluffy.
11. Have students compare the properties of the unpopped corn kernels with the popped kernels. Then engage in a collaborative discussion about what they think caused the unpopped corn kernel to change and questions they have. Chart student questions on the 2.1.C1: Student Question Chart. Use student questions to drive student learning. ESRs: Why did the kernel change? Did the heat cause it to change? Will it change back? Can we eat it?

12. To find out the answer to these questions, think about your kitchen at home. “Let’s name some other things that change when we heat them.” ESRs: a cake, brownies, cookies, pancakes, eggs, etc. Chart student responses.
13. Have students create a T-chart (see a model in 2.4.R2: T-Chart) to track what happens before and after heating each substance suggested by the students.

TEACHER NOTE

You can substitute similar foods based on your students’ ideas, such as brownie mix or cake mix, for steps 14–20.

14. Show students a package of pancake mix and some water. Pour pancake mix into a clear container. Have students observe the properties of the pancake mix. Have students share and record observations of the properties of the pancake mix on the Before side of the T-chart in their science notebook. Next, add water to the pancake mix and make a batter. Ask, “What do you notice about the pancake mix now?” ESRs: It is a liquid. It can be poured. It flows. It has bubbles.
15. Ask students, “What do you have to do to the batter to make it a pancake?” ESRs: You have to cook it. You have to heat it. My mom puts it on a griddle.
16. Show students a cooked pancake or display an image of a cooked pancake. Ask, “What do you notice about the cooked pancake?” Have students add in their science notebook the properties of the cooked pancake on the After side of the T-chart. Now, have them compare the properties of the cooked pancake with the properties of the raw batter. Ask, “Are the properties the same or different?” Chart student responses. Have students tell the story of the changing pancake mix, from a dry powder to a wet batter to something light, fluffy, and edible.

TEACHER NOTE

If appropriate for your class, provide the following sequence frame:

First,

Next,

Last,

For example: First, the pancake mix was dry and a solid. Next, we mixed it with water and it became a liquid. Last, it became a solid again once it was cooked.

17. Say to your students, “Let’s try something else!” Show students a raw egg. Crack the egg and pour it into a clear container. Have students observe the properties of the raw egg. Have students share and record observations of the properties of the raw egg on the before side of the T-chart in their science notebook. ESRs: It is a liquid. It is clear. It flows. It has bubbles. It has a yellow yolk.
18. Ask students, “What do you have to do to make it an egg we can eat? ESRs: You have to cook it. You have to heat it. My mom puts it in the microwave.
19. Show students a fried egg or display an image of a fried egg. Ask, “What do you notice about the cooked egg?” Have students add in their science notebook the properties of the cooked egg on the After side of the T-chart in their science notebook. Now, compare the properties of the cooked egg with the properties of the raw egg. Ask, “Are the properties the same or different?” Chart student responses underneath the responses in step 16.
20. Have students identify and discuss cause-and-effect relationships in the pancake and egg investigation. ESRs: Because it was heated, the raw egg (which was a liquid) is now a solid. It was flowy and now it is squishy because it was heated. The heat caused the egg to change.

TEACHER NOTE

If appropriate for your class, provide the following sentence frame:

_____ was _____, now _____ is _____ because _____.

21. Ask students to think about the three cooked foods: popcorn kernels, pancakes, and eggs. Ask students, “What is the same about how they changed?” Refer students to what they wrote in their science notebook (evidence) and the chart on the board. ESRs: They all spread out. They are all cooked. We can eat them. They can’t change back to the way they were before.
22. Explain that when we cannot change something back, it is an irreversible change. When we can change something back, it is a reversible change.
23. Have students add new understandings from this investigation and record in their science notebook whether the change in the cooked egg, pancake, and popcorn are reversible or irreversible changes. Encourage students to think about the pattern emerging from the three cause-and-effect relationships they have recorded in their science notebook.
24. Ask, “Have we answered our questions?” ESR: Yes, heat changes the things we eat, and we can’t change them back.

25. Ask students, “Can you think of other things that change when they are heated?” ESRs: Yes, I remember that happened with the ice cube. It melted in my cup, and then when I put the water back in the freezer, I got ice cubes again. Solid to liquid to solid! Oh, that happens with popsicles too!
26. Ask students, “What about chocolate?” ESRs: When I have hot chocolate, you can’t change it back. My Easter bunny melted, and I couldn’t get it to look like a bunny again. No, we can’t get it back just the same.
27. Have students observe the properties of a piece of chocolate in a snack-sized baggie. Have students think-pair-share their observations. Have students record their observations of the properties of the chocolate in their science notebook. ESRs: It is brown. It is hard. It is crunchy. It is a solid. It smells sweet.
28. Have students observe what changes occur to the chocolate when it is held in their hands (Note: They must keep the chocolate in the bag). If the chocolate doesn’t melt, ask students to think about what they might do to change the chocolate. ESRs: place it in the sun outside, rub my hands together, place it in hot water, heat it, microwave it, etc.
29. Have students take an action to heat their chocolate and then think-pair-share their observations. Have students record their observations of the properties of the chocolate in their science notebook. Have students identify and discuss possible cause-and-effect relationships.

TEACHER NOTE

If appropriate for your class, provide the following sentence frame:

_____ was _____, now _____ is _____ because _____.

For example, The chocolate was hard and solid, now it is soft and squishy because I put it in the sun on the windowsill.

30. Ask students, “Is the chocolate still solid? How do you know?” ESRs: It’s not a solid because it’s not hard. It’s not a solid because it spread out in the bag (like the liquids). I think we can pour it, so it’s not a solid (like the liquids).
31. Ask students, “Can we get the chocolate to be a solid again? What can we try?” ESRs: If we put it in the freezer, it can change. If we heat it more, it can change. It will be solid again if we keep it out of the sun.
32. Explore student responses and try out student ideas to determine if the change is reversible or irreversible, e.g., put the chocolate in the freezer, heat the chocolate more, put the chocolate in the blender, etc. Have the students observe the chocolate and answer their questions.

TEACHER NOTE

One way to carry out student ideas is to put the solid chocolate squares into a mold and melt the chocolate in the microwave. Then either leave it to cool and set or freeze it to cool and set.

33. Have students add new understandings from this investigation and record whether the change in the melted chocolate is a reversible or irreversible change in their science notebook.

34. Ask students what patterns they noticed about what happened to the chocolate when it was heated or cooled. ESRs: The sun caused the chocolate to melt and become a liquid. The microwave caused the chocolate to melt and become a liquid. The freezer caused the chocolate to become a solid again.

TEACHER NOTE

Help students relate the changed or melted chocolate to the anchoring phenomenon of the misshapen objects.

35. Distribute envelopes with the cut apart 2.4.G1: Student Claims to each group of four students. Have students read the student claims and select the one with which they mostly strongly agree or disagree.
36. Have the students in each group discuss their reasons for agreeing with the student claim they selected using evidence they have collected in their science notebook.
37. Students write a claim in their science notebook that some changes by heating or cooling can be reversed and some cannot. Students support their claim with evidence from what they gathered in Explore A, B, and C.
38. Have students cite specific evidence from their observations. Students may use drawings as part of their explanation. ESRs: The pancakes and eggs changed from a liquid to a solid and could not be changed back. This is an irreversible change. The popcorn kernel changed shape after it was heated, and it can’t change back either. That’s an irreversible change. The chocolate changed from a solid to a liquid and it became a solid again. This is a reversible change.

39. Refer students to the anchoring phenomenon: Materials are made of matter. We can observe misshapen objects, including a crayon, lip balm, and a candle. Have students refer to their observations of the regular objects and misshapen objects in Lesson 1: Properties of Matter.
40. Have students think-pair-share about whether the change in the misshapen objects is reversible or irreversible. Be sure to have students apply evidence from the investigations Explore A, B, and C in this lesson to make their predictions.
41. Have students respond in their science notebook. ESRs: They are like chocolate. I can heat them, and they change from a solid to a liquid. When I cool them they can get their shape back and be used for their purpose. I predict the misshapen crayon is a reversible change. I predict the misshapen lip balm is an irreversible change. I predict the misshapen candle is a reversible change.

42. Show students a slice of bread and a slice of toasted bread or show them 2.4.R1: Bread and Toast.
43. Ask students to make a claim (using words or pictures) about what caused the changes to the bread in the second picture and whether the change can be reversed using evidence from prior investigations. ESRs: The soft bread was heated and that caused it to become brown and hard. The change cannot be reversed. The evidence is that the changes weren’t reversed when the pancake batter, popcorn, and eggs were cooked. They couldn’t be changed back. Cooking seems to cause irreversible changes.