Filling Containers
5 min
Narrative
This Warm-up prompts students to compare four different objects and think about how they are similar and different from objects they have encountered in previous activities and grade levels. It gives students a reason to use language precisely (MP6). It gives the teacher an opportunity to hear how students use terminology and talk about characteristics of the items in comparison to one another.
Launch
Arrange students in groups of 2–4. Display the objects for all to see. If time allows, after 30 seconds of quiet think time, invite 2–3 students to briefly share what they notice all of the figures have in common (for example, they all look like three-dimensional objects). The purpose of this initial share out is to support all students in naming common attributes before they work to identify more specific features that a group of only three out of the four have.
Give students 1 minute of quiet think time, and ask them to indicate when they have noticed three shapes that go together and can explain why. Next, tell each student to share their response with their group and then together find as many sets of three as they can.
Student Task
Which three go together? Why do they go together?
Sample Response
Sample responses:
A, B, and C go together because:
- All have curved surfaces.
- All can roll if laid sideways.
- All look like a circle if held a certain way.
A, B, and D go together because:
- They do not have exactly 2 bases.
A, C, and D go together because:
- All have at least 1 flat surface.
- All could be modeled using paper.
B, C, and D go together because:
- If turned upside down, they look the same.
- They have no sharp points.
Synthesis
Invite each group to share one reason why a particular set of three go together. Record and display the responses for all to see. After each response, ask the class if they agree or disagree. Since there is no single correct answer to the question of which three go together, attend to students’ explanations, and ensure the reasons given are correct.
During the discussion, prompt students to explain the meaning of any geometric terminology they use, such as “side,” “edge,” “radius,” or “surface area,” and to clarify their reasoning as needed. Consider asking:
- “How do you know . . . ?”
- “What do you mean by . . . ?”
- “Can you say that in another way?”
Standards
- 8.G.C·Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.
- 8.G.C·Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.