Enzymes Help Us Digest Food

Ingrid Waldron
Type Category
Instructional Materials
Activity , Lesson/Lesson Plan
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 lesson is a sequence of learning activities that support student understanding of the role of enzymes in the digestive system and how the digestive system is supported by the circulatory system to provide nutrients to all cells. The lesson plan is divided into three laboratory activities each with separate probing questions. The first lab activity has background information, experimental procedures, results tables and interpretation questions.  Students design their own procedure and data table for the second and third lab activities. Extensive teacher resources are included and are a strength of this lesson sequence. Examples of resources include specific learning goals, teacher background information and flow charts. These three laboratory activities for students are appropriate for high school biology in an introductory unit on biological molecules or as an introduction to a unit on molecular biology.  

Intended Audience

Educator and learner
Educational Level
  • High School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

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 is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
This lesson includes background information that relates the function of enzymes to their role in the digestive system. Teachers will need to emphasize this connection to address this performance expectation. The model that is developed in the laboratory activities, particularly the two activities designed by students, connects directly to the function of enzymes in the digestive system and the connection between the digestive and the circulatory systems. The interpretation questions provided in each lab will also help teachers to emphasize this hierarchical relationship. Skillful teachers need to emphasize the connections between the absorption of digested food by the digestive system and the transport of food molecules throughout the body by the circulatory system. The transporting of these nutrients to all cells by the blood is a connection between molecules, cells and body systems that should be emphasized in relationship to this performance expectation.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
In the first lab activity students interpret evidence to test the given probing question. For the probing questions to be effective, teachers must provide students with time to think about their answers. Teachers could utilize a think-pair- share between students to discourage student guessing. In experiment one teachers need to emphasize the predictive portion of this lab. For the second and third laboratory activities students design and carry out their own procedure to answer the probing questions about lactase. Teachers need to have all materials and supplies for the hands-on activities available and should complete all the lab activities themselves before the students do so. Having the students do the first lab activity will help the students feel more comfortable with the designing of their labs to address the other two probing questions. A fourth resource for having the students designs their own lab activity as an extension or supplementary lab activity is included at the end of the teacher resources. The author suggests that this depends on student readiness as a tip. However, no suggestions for determining student readiness are provided so teachers will need to be sure students were successful with the second and third parts of their labs before proceeding to the extension activity.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
This lesson supports this disciplinary core idea that multicellular organisms have a hierarchical structural organization, in which any one system is made up of numerous parts and is itself a component of the next level. Enzymes have a very specific shape and function and can only work on one substrate. Enzymes are a vital part of the chemical reactions that support life. In this instance a digestive enzyme lactase will only work with the conversion of milk sugar, lactose, into a simple sugar. This is an essential part of milk digestion. The breakdown of larger compounds into small enough particles or compounds that can cross the membrane of the small intestine and move into the capillaries of the blood vessels is the basis of digestion. Food molecules are then transported to cells by the circulatory system. This illustrates the connection and interaction between the levels of organization: enzymes acting on food molecules, cells of an organ, specifically the small intestine and the digestive system and circulatory system in a hierarchical structural relationship. Connections between the digestive and circulatory systems must be an emphasis of this lesson.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
This lesson provides students with three probing questions, one for each lab experiment: (1) “Can the sugar lactose be digested without any enzymes?” (2) “Can the same enzyme digest lactose and sucrose?” and (3) “Does the enzyme lactase digest sugar in milk?” Teachers are encouraged to utilize the information provided in the teacher notes to help students in addressing these probing questions. This will help students organize their design portions. The structure of enzymes as related to their function is emphasized. The interpretation questions also place emphasis on the relationship of structure and function of enzymes as well as the relationship of structure and function in the digestive system. The interpretation questions help students make relationship connections. Skillful teachers can also emphasize these relationships by asking additional questions of students and having students elaborate on what is learned in their laboratory activities and complete a peer review of other students’ results. Students could research other enzymes that function in the digestive system as additional connections to the crosscutting concepts.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This lesson utilizes laboratory activities to provide students with opportunities to relate structure and function to body systems. Two of the laboratory activities developed around a probing focus question are designed by students. These activities directly relate to the relationship of structure and function to the organization of interacting systems; specifically the connections between the digestive and circulatory systems. Connections to the all three dimensions of the Next Generation Science Standards are provided as the crosscutting concepts, the Disciplinary Core Ideas and the practice are all explicitly addressed. Teachers are encouraged to keep these dimensions in the forefront of the lesson as emphasized in the key concepts and goals provided by the author. Teachers are encouraged to explore the provided resources in the teachers’ background information prior to teaching the lesson to support students’ designing the second and third laboratory activities. Student design is an important aspect of this lesson.

  • Instructional Supports: All of the activities, focus questions, diagrams and interpretation questions are purposeful and well chosen. The resources for teachers are extensive and very well done. Key concepts, learning goals and teaching approaches contribute positively to instructional resources. Connections to the Next Generation Science Standards are emphasized by providing probing questions and guidance for successful implementation of student-designed lab activities. Students’ active involvement and questioning is sparked when students complete laboratory activities of their own design and teachers need to utilize this aspect of this lesson. Students designing the procedures for parts two and three are the portions of this lesson that add strength of alignment to the three dimensions of the Next Generation Science Standards. Strength of alignment could also be increased by building the whole lesson around the phenomena of “how cells get energy and nutrients from the interaction of the two emphasized body systems”. Many additional resources are added to the teacher background information for teachers not familiar with the content or laboratory procedures. Teachers may need to develop supportive questions and may also need to lead students through the flow charts. While teachers rotate from lab group to lab group, teachers should pay special attention to the key concepts and learning goals while developing and asking additional supporting questions of students. At the end of student materials there is a section on lactose intolerance which is a strong real world connection between genes and enzymes. There may even be a student in the class or a family member of a student who has lactose intolerance. No explicit ideas for differentiation are provided. One way this could be addresses is by encouraging further student research on other enzyme related issues such as pet digestive disorders could be used for additional enrichment of the lesson. Enzyme function relating to genes could also serve as a lead in to DNA, genes and enzymes. Introductory materials for background are given for the students and students are challenged to utilize the background material and their lab results to answer the interpretation questions for each lab. In addition to background and supporting reading material relevant flow charts and diagrams are included in each student section. Extensive teacher resource information is provided in the file of teacher preparation notes and is the strongest aspect of this resource. Teachers need to keep in mind the three dimensions of the Next Generation Science Standards while utilizing these resources. Resources include prior background information for student understanding, learning goals, connections to Next Generation Science Standards, extensive background readings for the instructor including flow charts and diagrams some of which can be used with students. Additional web resources that identify related activities and extensions are also included. The author will provide answers for all student interpretation questions upon request. While all of the student materials and teacher notes are available online it is helpful that the answers to the student interpretation questions are not available to students and are reserved for teachers only.

  • Monitoring Student Progress: The interpretation questions provide teachers with a means for assessing student understanding and assessing student progress. Skillful teachers will need to develop questions for monitoring student progress while developing their student lab design. Interpretation questions should help students make connections between enzymes and their function and role in digestion but teachers may need to expand on these questions as well as including the questions that emphasize the connections between body systems. Depending on the academic levels of the students, teachers may need to develop checklists or guides for monitoring students’ understanding of concepts.

  • Quality of Technological Interactivity: This lesson is not technology based but could engage students with technology by watching video clips identified in the teacher notes.