Three "M"s: Models, Microscopy, and Measurement!

Lesson Content

• Lesson Plan Template:

  General Lesson Plan

• Learning Objectives: What should students know and be able to do as a result of this lesson?

  
  

  Upon completion of the lesson, the student will be able to:

  • Define and distinguish the difference between magnification and resolution.
  • Calculate approximate specimen size at various microscopic magnifications.
  • Describe typical ocular magnification of a light microscope.
  • Identify the basic parts and functions of a light microscope.
  • Compute total magnification when given ocular and objective powers.
  • Estimate the size of a specimen when given the amount of space it occupies and the diameter of the field of view.
  • Describe what happens to the orientation of a specimen on a slide, when viewed through the ocular as opposed to the being viewed with the unaided eye.
  • Demonstrate ability to use the metric units used in microscopy by converting between units.

• Prior Knowledge: What prior knowledge should students have for this lesson?

  
  
  • Students should be familiar with the parts of a light microscope and/or dissecting scope, be able to perform simple equations to solve mathematical problems, and have been exposed to metric (SI) units.
  • They should review the safety rules when working in a laboratory setting as well as proper handling techniques for microscopes.

• Guiding Questions: What are the guiding questions for this lesson?

  
  

  Some guiding questions for the lesson that the teacher can ask students/student groups/whole class either before (B), during (D), or after (A) the lesson include:

  • What are some of the limitations scientists are faced with when trying to solve the mysteries of cellular function? (B)
  • When viewing living cells with functioning organelles, why would an SEM or TEM not be helpful for the scientist? (A)
  • Why does microscopy involve standardized measurements? (B, D, A)
  • Why would students need to learn the metric units of microscopy? (B, D, A)
  • What are some of the limitations of a compound light microscope? (A)
  • What are some of the limitations of an SEM or TEM? (D, A)
  • What are some of the benefits of using a compound light microscope? (A)
  • Do you know the functions of the parts of a compound light microscope? Can you explain them? (B, D, A)
  • Is anyone capable of computing the size of a specimen when moving from one power to another? (B, A)
  • Can you convert from millimeters to micrometers with accuracy and ease? (A)

• Teaching Phase: How will the teacher present the concept or skill to students?

  
  

  As the introduction of the unit, the students will each receive a copy of the Word Splash. Each student will work independently to write what they believe is a good definition below each term. Students will then Think Pair Share and find a partner across the room. The pair of students will sit together and read their peer's definitions silently. Then they will select the one they feel is the better definition and circle the definitions they selected. Each pair will need to be prepared to share one definition for each term and use the overhead projector to explain their definition to the class. For example: Student pair #1 circled the definition from student A for the term "nosepiece." Student A's definition was, "The part of the microscope where the objectives are found." The teacher may then ask the class if any other group has a similar yet different definition or lead students to the textbook's definition of the structure. This will allow the teacher to go over each term while students benefit from sharing their ideas. The teacher may chose to move randomly around the room and call on different partners to share until all terms have been defined and discussed.

  The target audience for this lesson plan is 9th/10th graders enrolled in a Biology 1 or Biology 1 Honors course. The activity can be introduced to students using a teacher-made PowerPoint, allowing students to browse (if computers are available), or by initiating a teacher-lead discussion.

  The teacher will want to ask probing questions similar to those below:

  1. What do you notice about some of the images viewed here?
  2. Do you think that all of these images were photographed using the same type of microscope? Why or why not?
  3. Which images allow you to really see internal features?

  
  Students will divide into groups of 4-5 and move to one of the six stations set up around the classes. Students will be allowed 20-30 minutes to complete the activities at each station before rotation to the next. Students at station 1 move to 2, 2 moves to 3, and so on. Station 6 rotates to station 1. Students will complete a worksheet/exit slip at each station.

  Station 1

  • Students will use laptops, iPads, a SmartBoard, or other Internet device to complete the tutorial Virtual Urchin at http://virtualurchin.stanford.edu/index.html. Students will review the parts of a microscope, learn about the field of view, and simulate how to use total area in the field of view and ocular/objective powers to estimate the size of a specimen.
  • Remind students that no two microscopes are the same. Therefore, the calculations they perform on Virtual Urchin are based on the microscope used in that demonstration. Each microscope must be calibrated independently of any other. Remind students that the image seen through the eyepiece is inverted (up/down) and reversed (left/right).
  • Students will fill out the Station 1 Worksheet; an answer key has been provided.

  
  Station 2

  • Students will practice labeling laminated microscope diagrams with the names of the parts. Students will redo those diagrams until they feel they have mastered matching naming the structures of the light microscope.
  • They will then label their own diagram of a microscope to turn in.
  • There are many examples of worksheets on labeling the parts of microscopes availible online. Teachers can download an unlabeled microscope diagram here. An answer key can be found here.

  
  Station 3

  • This station will have a variety of articles about microscopy. Students will read two articles and then write a summary of both articles. This will give students an opportunity to practice writing summaries of scientific articles. These summaries will serve as the exit slip for this station.
  • Articles may be obtained from a variety of sources including the following sites:
    • http://www.microscopy.org
    • http://www.laserfocusworld.com/topics/microscope.htm
    • http://www.nature.com/ncb/journal/v11/n10/full/ncb1009-1165.html
    • http://www.bioopticsworld.com/articles/2014/03/analysis-method-tracks-biological-particles-in-cell-microscopy-images.html

  
  Station 4

  • Students will practice matching microscope structures on functions on laminated copies of the Station 4 Worksheet. An answer key has been provided.
  • Before leaving this station, students will complete their own unlaminated copy of this worksheet, which will serve as an exit slip.

  
  Station 5

  • This station will have three prepared slides, one each of a paramecium, eulena, and amoeba, as well as pictures of each organism. These slides will not be labeled. It will also have labeled diagrams of each organism such as the one found here.
  • Students will follow the directions on the Station 5 Worksheet to focus the microscope on the slide, asking the teacher for assistance, if needed. They will then draw the specimen on their worksheets.
  • Next, students will review the diagrams and select which select which organism most resembles the specimen they are viewing. They will then use the diagram to label their drawings.

  
  Station 6

  • Students will select five items from their personal belongings or from a set of items at the table. They will then use ruler to measure those items in centimeters. Students will record the object names and measurements on the Station 6 Worksheet. Students will be asked then to convert those measurements into millimeters and micrometers.
  • Since students are using their own personal items, a key is not included here. If you elect to give students a selection of objects to choose from instead, then you could create a key and allow students to check their answers.

  
  Extension Lab: Whole class activity

  • This optional extension lab will guide students to use computation skills to estimate the size of an object in the field of view of a light microscope at various magnifications. An answer key has been provided.
  • Each group will use a Petri dish as a model for a microscope's field of vision. After measuring the dish in centimeters, they will use a penny and a paperclip to practice estimating the size of an object in a microscope's field of vision. They will then transfer these skills to estimating the size of an object viewed under a microscope.
  • An alternate final assessment has been provided if teachers wish to assess the skills developed in this lab; see the Summative Assessment section.

• Guided Practice: What activities or exercises will the students complete with teacher guidance?

  
  
  • Students will have opportunities for guided practice at each station.
    • Student groups will use the microscope tutorial on the Smartboard or laptop at Station 1 with teacher assistance.
    • At Station 2, students will label the microscope using laminated diagrams so that they can wipe them clean and practice again.
    • At Station 3, students will read two articles at their station and write one summary
    • At Station 4, students will label a diagram of a typical compound light microscope and check their work.
    • Station 5 has students focus on a selected slide while following written instructions to draw and label their specimen.
    • At Station 6, students will learn about metric conversions by measuring in centimeters and then converting those measurements to millimeters and micrometers.
  • The teacher will review how to work the first three problems on the practice problems worksheet that is taken home for independent practice. See the Summative Assessment section.

• Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the lesson?

  
  
  • Students will take home practice problems that reinforce unit conversion, as well as the computation of specimen size and total magnification.
  • Students will design and construct a  with images of microscope parts and descriptions of how they are used to view a specimen. Students will share these blogs on the teacher's Weebly and the class will view each others' blogs as an extension of independent practice. Comments will be shared in a round-robin event during the beginning of the next learning session. See the sample blog. A rubric has been provided to assess the blogs; see the Summative Assessment section.
  • Students will read a description of microscopy and relative size by the photographer Dennis Kunkel. Students may then look at various photos taken on SEM, TEM, and light microscopes.

• Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?

  
  
  • The teacher will wrap up the lesson by sharingsamplesofstudentvocabularyblogs with the class and give specific examples of why these are effective in conveying a complete understanding of the structures/functions of microscope parts, the three types of microscopes, and microscopy terminology.
    • Teachers might want to refer to the during this discussion, or depending on students' needs, it could be used as a tool to help students as they write their own vocabulary blogs. Scoring the blog may be done using the rubric found in the Summative Assessment section.
  • The teacher will ask for volunteers to discuss what was learned at each of the six stations. Copies of the keys for each exit slip may be reviewed via projector, Elmo, or Smartboard.
  • Students will be asked to complete a Marzano 3-2-1; they will list 3 things they learned, 2 things that surprised them, and 1 thing they still would like to know about microscopy.

• Summative Assessment

  
  

  Opportunities for summative assessment do not need to be limited to those listed below:

  • Students will have several opportunities to work with their peer groups to practice microscopy vocabulary using laminated microscope diagrams.
  • Student exit slips may be used as summative assessments, if desired.
  • Students will complete practice problems at the conclusion of the lesson. An answer key has been provided.

  Extension via Lab:

  • If the teacher chooses to use the extension lab, then he or she may also wish to use the extension final assessment, which incorporates skills from the extension lab. An answer key has been provided.

  Extension via Homework:

  • Students may use a free blogging platform to create a blog with vocabulary definitions and images using photos they take of the microscope and its parts. See the . The teacher should consider student access to the Internet before choosing this assignment. A rubric for assessing the blog has been provided.

• Formative Assessment

  
  
  • Teachers should administer the attached Pre/Post Unit Test before and after the lesson. An answer key is provided.
  • Teachers can maximize student success and engagement when student groups are arranged with high-middle-low achievers. It is suggested that the teacher use 8th grade science FCAT data when forming groups for the station activities.

• Feedback to Students

  
  
  • The teacher should monitor students' understanding by regularly monitoring students' oral/written responses during guided instruction to clarify misconceptions that arise during the reading and while analyzing microscopy estimations.
  • Students should complete daily exit tickets explaining what they have learned and what areas of the lesson need further clarification. After reading students' exit slips, the teacher will provide further clarification and revisit areas that require further re-teaching.
  • The teacher will provide feedback during the word splash, an introductory activity, allowing students to revise and edit their own writing.
  • The teacher should place 10 pre-measured items out for students and generate a key for use at the close of the lesson. List the centimeters (cm), millimeters (mm) and micrometers (µm) beside each item. Show students the items and then review conversions from cm to mm and then mm to µm.