Grade 2 | SCIENCE
WEEK 16 • TEACHER GUIDE AND ANSWER KEY • DAYS 76–80
Read each lesson aloud with the child and model the worked example before practice. Do not show this key during practice. Accept oral, drawn or written answers where the child cannot yet write the whole answer. On Day 80, read aloud if needed but give no hints.
Week 16 Student Textbook | Week 16 Practice Workbook | Week 16 Teacher Guide | Week 15 Student Textbook | Grade 2 index
Day 76: Heating Changes Matter: Melting
Standard: Grade 2 Science Standard 4, 2.4
Practice record: Sample results: 30 minutes in a sunny window, printed on the Week 16 Practice Workbook.
Worked example: A snowman melts on a sunny day. What made it change? Worked answer: Heat from the sun.
- The ice cube and the chocolate chip (the butter softened).
- The crayon and the pebble.
- The ice cube started as a solid. The warmth of the sun melted it, so it became liquid water. Accept any answer that says heat changed the solid ice into a liquid.
Teaching note: Results vary with the weather. Use only sunlight or a warm room for this lesson. An adult does any heating with a stove, oven or microwave.
Day 77: Cooling Changes Matter: Freezing
Standard: Grade 2 Science Standard 4, 2.4
Practice record: Sample observations, printed on the Week 16 Practice Workbook.
Worked example: A puddle has turned to ice on a cold morning. What made it change? Worked answer: Cold air froze the water.
- It froze into a hard, solid cube.
- It melted back into liquid juice.
- Yes, it can be undone. The juice was a liquid, froze into a solid, and then became a liquid again when it warmed. Accept yes with evidence from the three observations.
Teaching note: No heating is needed today. Use the observation checklist below.
Hands-on task observation checklist (Freeze juice and let it melt). Check each item you observe. Four or five items shows the child met the task goal; two or three means repeat the task with support.
- ☐ Child observed and recorded the juice before freezing.
- ☐ Child observed and recorded the frozen juice.
- ☐ Child observed and recorded the cube after it sat out.
- ☐ Child used solid and liquid correctly.
- ☐ Child decided whether the change can be undone and gave evidence from the table.
Day 78: Changes That Can Be Undone and Changes That Cannot
Standard: Grade 2 Science Standard 4, 2.4
Practice record: Before and after observations (an adult did all the heating), printed on the Week 16 Practice Workbook.
Worked example: A wax candle stub is warmed by an adult until it is soft. When it cools, it is hard wax again. Can this change be undone? Worked answer: Yes, because the wax went back to how it was before.
- The water and the butter.
- The egg and the toast.
- Example: The egg was runny before cooking and firm after. When it cooled, it stayed firm, so cooking an egg cannot be undone. Accept any material with a correct decision supported by its before and after observations.
Teaching note: Let the child decide each answer from the table before you discuss it. Do not tell the child which changes can be undone; ask what the observations show.
Day 79: Evidence Test: Chocolate and Dough
Standard: Grade 2 Science Standard 4, 2.4
Practice record: Sample observations, printed on the Week 16 Practice Workbook.
Worked example: Why must an adult do all the heating in this test? Worked answer: Because heating can cause burns, and an adult can do it safely.
- Hard, solid chocolate again, in a new flat shape.
- Firm, crisp and brown; it did not turn back into soft dough.
- Melting chocolate can be undone: it went from hard, to liquid, and back to hard when it cooled. Baking dough cannot be undone: it went from soft to firm and brown and stayed that way after cooling. Accept both decisions with evidence from the before and after observations.
Teaching note: An adult does all heating, and the child watches from a safe distance. Let the child decide from the observations before you discuss it. Use the observation checklist below.
Hands-on task observation checklist (Compare melted chocolate and baked dough). Check each item you observe. Four or five items shows the child met the task goal; two or three means repeat the task with support.
- ☐ Child stayed back while the adult did all the heating.
- ☐ Child recorded observations before heating.
- ☐ Child recorded observations during heating.
- ☐ Child recorded observations after cooling.
- ☐ Child decided which change can be undone and supported it with the recorded observations.
Day 80: Independent Check: Heating and Cooling
Standard: Grade 2 Science Standard 4, 2.4
Practice record: Before and after observations (an adult did all the heating), printed on the Week 16 Practice Workbook.
Worked example: Ice is left in a warm room. What happens to it? Worked answer: It melts into liquid water.
- The broken crayon pieces.
- Still a firm pancake.
- Can be undone: the crayon pieces (or the ice pop) melted into a liquid and became a solid again when cooled. Cannot be undone: the pancake batter became a firm pancake and stayed firm after cooling. Accept one correct example of each with evidence from the table.
Teaching note: Independent check: read aloud if needed, but give no hints.
Week 16 Student Textbook | Week 16 Practice Workbook | Week 16 Teacher Guide | Week 15 Student Textbook | Grade 2 index
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