Saltine Lab

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Objective

Students will examine the process of hydrolysis and relate it to digestion and metabolism of carbohydrates.

Big Idea

Even if you don't chew that cracker, it will be hydrolyzed and digested.

Warm-Up

5 minutes

Warm-Up:  Polymers are like____ because_____.    Monomers are like___ because_____.

Ask students to complete this Warm-Up as a strategy to review content from the Monomers make Polymers lesson.  Allow students to work on their responses for 1-2 minutes before verbally checking to see if most students have completed the similes.  Ask for volunteers to share what they placed in the blanks.  Listen to see if students made reasonable associations with the characteristics of monomers and polymer with the things that they indicated that they are like.  Pay attention to how students complete the second part of the simile.  It will explain the “why” of their reasoning and reflect their depth of understanding about monomers and polymers.

Introduce New Material

20 minutes

Inform students of the learning targets for this lesson:

  • I can explain the structure and functions of carbohydrates.
  • I understand the process of hydrolysis and how it relates to the digestion and metabolism of carbohydrates.

Display visual information as you provide information about the structure of the carbon molecule and how its structure allows it to form macromolecules that perform vital functions in cells. Distribute guided notes for students to use to capture the key points during instruction.  Guided notes provide greater support for the different learning styles of students. 

Explicitly teach the term macromolecule by comparing and contrasting the prefixes, micro- and macro-.  Make sure that students know that macro- is the opposite of micro-.  Ask students to think of terms that use the prefixes micro- or macro-. Be prepared to share a few terms like microscopic, micro-miniskirt, or macro-evolution. 

Provide “just in time” instruction for the lab that will occur later in the lesson by presenting information about the characteristics of the macromolecule group, carbohydrates.  Walk around during instruction to ensure that students are on task and writing down the key points.  Use of a digital pen and mmPad are important tools that allow teachers to use the whiteboard without remaining stationary at the board.  Moving around the room during instruction is always a great tool for proximity control.  It also helps in identifying positive behaviors that should be recognized.

Check for understanding by asking, “If some carbohydrates are macromolecules, are they also polymers?  Allow 2-3 students to share their thoughts.  It is not enough that students respond “yes” to this question.  Make sure that students are also able to defend their response with explanations that explain the “why”.  This question measures students’ ability to use their prior knowledge about monomers and polymers  in order to connect it the meaning of macro-. 

Share a video, Carbohydrates (source, Discovery Education).  Before watching the video, instruct students attention to the video quiz questions at the bottom of the guided notes.  Perform a quick preview of the questions before viewing so that students will know what questions they will be asked to answer.  Pre-reading the questions helps students actively watch videos with greater focus and purpose. 

Note: I minimize the use of paper by putting the video quiz questions on the same paper as the guided notes.  I make it point to remind students that they are not limited by the space on the page in writing their responses to the questions.

At the end of the clip, perform a “round robin” activity is which the teacher starts the rotation by selecting the first student to respond to the question, then that student selects another student to read and respond to a question after he/she has answered one of the quiz questions.  Consider adding an element of fun and engagement by having students throw and catch a plastic ball as a method of selecting the next student to read and respond to the question.  The prospect of throwing and catching a ball in class may be enough to draw the reluctant participant into the discussion.  This activity is fun and effective as a formative assessment that will indicate if students require a spiral review of content before moving into guided practice.

Guided Practice

5 minutes

Inform students that they will engage in a lab, working in groups of two. Display the Saltine Lab procedure on an LCD projector and distribute hard copies of the lab, as well.  Summarize the lab procedure.   

Use “think aloud” modeling to answer the first 1-2 questions on the lab.  This practice may not be needed by all students but it helps those students who could benefit from observing the thought process that is used to answer the questions correctly. Inform students that the first 7 questions will need to be completed before moving into the experiment stage of this lab.  It might be effective to require students to bring the 7 completed questions to the lab station for verification before picking up their lab materials.

Independent Practice

20 minutes

Instruct students to perform a close read of the Saltine Lab Procedure  and questions before beginning the lab.   It may be helpful to have students underline or highlight the questions during the close read.  This practice will help them progress through the lab more purposefully.

Release students to work on the lab. Remind students to begin with questions 1-7.  Walk around to observe students as they work.  Look for student behaviors and conversations within the small groups that suggest understanding or misconceptions. While students are conducting the lab and completing the analysis questions.

Remind students to answer the remaining questions from the lab after eating the cracker and juice.  Give students 20-25 minutes to complete this activity. 

As students work, walk around to observe student actions and conversations.  Offer assistance in the form of guided questions as needed based on your observations. Instruct students who complete the lab activity before the designated time ends to begin work on the constructed responses in the Lesson Close.

The student work 1 and student work 2 samples that are included are included to show that students are able to use the academic vocabulary appropriately in their responses to the questions.  Both samples also indicate understanding of the difference between monomers and polymers, as well as the difference between monosaccharides and polysaccharides.  The only misconception that appears to be consistent between both student work samples is that amylase is the main ingredient of saliva.  This suggests that when discussing digestion, I focused my discussion on the presence of the enzyme and failed to make it clear to students that the main ingredient of saliva is water.    This represents a need for clarification that should be noted when students return to class.


Close

5 minutes

Display 3 writing prompts.  Read each writing prompt aloud.  Instruct students to answer 1,2 or all 3 prompts, depending on the abilities of the students and the time remaining in class:

  • Explain how you get glucose from a polymer.  Be specific and use correct terminology.
  • Explain how sucrose is made.  Be specific and use correct terminology.
  • How do you think hydrolysis would be affected if a person’s salivary glands were unable to produce saliva?  Explain.

A review of students’ constructed responses will indicate whether the students have attained the learning targets.