Which Will Dry Out Last Assessment Probe

Page Keeley
Type Category
Assessment Materials Instructional Materials
Lesson/Lesson Plan , Assessment Item
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



This is one of 25 assessment probes from the book, “Uncovering Student Ideas in Life Science, Volume 1: 25 New Formative Assessment Probes,” by Page Keeley and co-authors. All assessment probes in this collection are aligned to a particular science concept and field-tested by several teachers in classes of diverse student backgrounds. The “Which One Will Dry Out Last” assessment probe is written in the format of a prediction probe, asking students to predict which of the three shapes of bacteria will dry out last. Students are asked to choose what they think is the best answer of the three bacteria pictured and then explain their thinking and reasons why they selected their chosen answer. The purpose of the probe is to elicit students’ ideas about loss of water through cells. Students should be told that all three bacteria have the same volume and that it is the shape of the three bacteria that is different. This formative assessment probe elicits whether or not students think that shape, surface area and volume relates to water loss through cells and student ideas about the relationships between shape, surface area and volume. The teacher notes also provide suggested ways to extend student thinking by providing three-dimensional objects or by having students make three dimensional models of the bacteria with clay. An assessment probe is a purposefully designed, multi-grade level question that asks students to provide a two-part response. Part one consists of a selected response, and part two asks students to provide an explanation. This format helps teachers identify students’ existing ideas about phenomena or concepts, which can help inform the design of instruction. Assessment probes can also be used to engage students, encourage thinking, and promote sharing of ideas. When implementing probes in the classroom, the authors suggest using the probe to encourage teacher-student, student-teacher, and student-student feedback on learning.

Intended Audience

Educator and learner
Educational Level
  • High School
Access Restrictions

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Performance Expectations

HS-LS1-2 Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.

Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This assessment probe may be used in a learning sequence that helps students deepen their understanding about water loss in cells. The probe elicits students’ ideas on the relationship between shape, volume and surface area. When administering the probe, several ideas for teachers to enhance student understanding are included. Ideas include showing the students pictures of 3-D bacteria and showing the students objects with the same volume but different shapes, i.e. a rope, a stick and a bowl. Assessment probes are designed to be integrated into classroom instruction. Their purpose is to promote student thinking and open up opportunities for learning. They are best used at the beginning of instruction to elicit students’ prior knowledge and during instruction to monitor developing understanding. Assessment probes provide the teacher with information about what students think about a concept, not only revealing incorrect responses, but also partially correct, or correct responses and reasoning. These data can be used by the teacher to modify instruction and/or provide feedback to students. Assessment probes should never be graded, as this diminishes their utility as formative assessment tools.

Science and Engineering Practices

This resource appears to be designed to build towards this science and engineering practice, though the resource developer has not explicitly stated so.

Comments about Including the Science and Engineering Practice
By administering a probe at the beginning and during instruction, the teacher is making student thinking explicit as students inquire about a specific phenomenon. It is helpful to invest the time to allow all student ideas to be made public, e.g. by posting the answer choices on a chart in front of the class and engaging students in a discussion of the justifications for each of the choices. This creates a culture of learning, where individuals’ ideas are valued in contrast to the “correct” answer. Encouraging students to discuss the different answers and justification with a partner or in small group, or as a class, supports the development of productive talk in the science classroom. It encourages students to take risks, listen carefully to each other, and encourages the learner to continue to reflect on their own learning as the lesson unfolds, and thus promotes a safe classroom environment, building a community of learners. For this assessment probe, asking students to evaluate which one of the three bacteria pictured will dry out last and to justify their selected claim will support students in clarifying their own ideas about the relationship of volume, shape and surface area. To take full advantage of this learning opportunity, teachers will need to engage students in small-group and/or whole-class discussions of the various claims and underlying processes.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
The DCI addresses the hierarchical organization of multicellular organisms. This specific probe asks students to identify the relationship between the volume and surface area of bacteria to the drying out of the bacteria. Teachers will need to help students make the connections between the shape, surface area and volume of bacteria and correlating surface area and volume of cells within multicellular organisms to the survival of the organism. The emphasis must be on the relationship of the organization of the organism to its survival. While the selected response of the probe explicitly connects changes in the physical environment of the cell to survival of the cell, the student explanations asked for in the probe, implicitly connect to the other main points of the DCI of structure and function. Through additional questions and/or activities, and depending on the goal of the lesson, the teacher can guide students to make these connections more explicit. This might occur as part of discussions of the probe or in subsequent learning activities. Cells of muticellular organisms have a limit of surface area to volume ratio. This website provides an excellent illustration: http://www.brooklyn.cuny.edu/bc/ahp/LAD/C5/C5_ProbSize.html

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
This assessment probe provides a great opportunity for students to link the specific example (which of the three bacteria will dry out the last) to the general crosscutting concept of the relationship of structure and function of all cells including those in multicellular organisms. This probe can lead directly into a discussion and an activity to determine the relationship of cells to their surface area and volume for the exchange of nutrients and wastes.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This assessment probe builds on the claim-evidence-reasoning framework and asks students to evaluate multiple claims before identifying and supporting the best claim. Therefore, the probe makes a strong connection to the practice dimension of the NGSS. The connection to the DCI is strong, but only explicitly addresses part of the DCI. The connection to the CCC is present, but the task only asks students to select a claim and provide an explanation, based on their own prior knowledge. The teachers will need to provide additional learning activities for students to provide stronger connections to the disciplinary core idea and crosscutting concept.

  • Instructional Supports: The probe engages students in deciding and defending which bacteria cell the students think will dry out last. This same reasoning can apply to the cells of multicellular organisms. Thinking about a specific shape, volume or surface area when they make their claim, helps students identify their reasoning. By asking students to transfer their current understanding of the concept of volume and surface area , student responses will reveal how fragile/firm their understanding of the science concept is. Use of this assessment probe is one of the instructional strategies in an instructional sequence that can include investigations, models/simulation, reading, or analyzing real data. Revisiting the probe at the end of the instructional sequence, will support students in monitoring their own learning, especially if students are being asked to share with each other what changes they made to their explanation. The accompanying teacher notes provide good content background, a progression of student understanding from elementary to middle school to high school, common misconceptions, and suggestions for implementation and instruction. Providing a context with which students can identify is helpful for English Language Learners. Student responses to the assessment probe can be used to differentiate instruction. Using a probe does not always have to involve writing. Alternatives include listening to students discuss probes, observing students test ideas from the probes, and having students draw their ideas.

  • Monitoring Student Progress: The teacher notes discuss expected student understanding at different grade bands but not at different levels of understanding within those grade bands, and a rubric is not provided. Correct response and explanation is provided in the teacher notes. The information gained from the student responses to this probe should provide useful information to plan and adjust instruction. The teacher notes contain some specific suggestions for instruction and assessment, e.g. to compare and contrast with students the everyday common use of volume and surface area with the scientific meaning of the words. Based on their selected response answer choices, students could be assigned or self-assign to different answer choices and discuss explanations with other students in that small group. A large group discussion of the class choices and their explanation can be a good start to come to consensus of what the class thinks at the outset of instruction, as students are making arguments for and against different choices. The responses can be revisited as instruction progresses and students can suggest that certain choices should be removed based on evidence gathered during the activities.Plotting student responses anonymously via a response system or post-it notes create a safe classroom environment and separates the ideas from the individual students, which in term promotes risk-taking.

  • Quality of Technological Interactivity: This is not a technology-based resource. However, the probe could be administered through online technologies (e.g. Google Forms, which would facilitate the teacher’s ability to analyze and respond to class-level data generated through this assessment.