Sea
Urchins & Mitosis
Unit
Plan
By:
Mark Franano & Brian Ortiz
Subject: 7th Grade Life Science
Estimated Lesson
Time: Five 55 minute Class Periods
State Content
Standards:
1c. Students know the nucleus is the repository for genetic information in plant and animal cells.
1e. Students know cells divide to increase their numbers through a process of mitosis, which results in two daughter cells with identical sets of chromosomes.
Lesson Objectives: The student will be able to identify all 6 stages of cell division and
mitosis both in a drawing and in a laboratory setting.
Key Vocabulary:
Any and all vocabulary that is associated with mitosis. Including but not limited to: mitosis, interphase, prophase, metaphase, anaphase, telophase, cytokenisis.
Anticipatory Set:
Students will be told that they will be working with live specimens to complete this unit. This is a special privilege and any one who does not act appropriately will receive a lab safety citation.
Input:
Day 1, 2 and half of 3: The teacher will go over notes in front of the class regarding the process of cell division and mitosis. This will include and explanation of each of the six phases: interphase, prophase, metaphase, anaphase, telophase, cytokenisis.
Modeling:
The teacher will model good note taking strategies. They will also emphasize getting all of the information and adding their own notes to make the notes more meaningful.
Input:
Second half of Day 3: The teacher will explain the purpose and procedure of the next two days of lab activity. The students will be told that they will be working with live specimens, purple sea urchins (Strongylocentrotus purpuratus) or any other urchin that is available. The specimens were collected with a viable state collecting permit and are not in any way endangering a species population or ability to survive. The students will be told that the teacher will be injecting the urchins with Potassium chloride (KCl) in order to get them to release their gametes. This process will inevitably kill the urchin but it does not have a developed nervous system like we do so it does not hurt the urchin. They will be told to not anthropomorphize the urchins.
Once spawning has occurred the teacher will then mix the gametes from the male and female urchins to get them to fertilize each other. For their lab the students will need to find examples of the 6 stages of mitosis as they see them in the fertilized zygotes of the urchins.
The students will set up their lab books with the title of the lab (Sea Urchin Mitosis) purpose of the lab (to use a microscope to see all of the stages of cell division and mitosis) and procedure (as preformed on day 4 and 5). For the data the students will draw 6 circles to represent the 6 stages that they are to find. They will label each with the appropriate stage in order from interphase to cytokinesis. They will be told that they are to make a very detailed, colorful (if appropriate) drawing of what they see. If they see it they must draw it!
Day 4: The teacher will start class by reminding the students of the proper use of the microscopes and of proper lab rules that are appropriate to this lab.
The teacher will then inject the urchins with the KCl to get them to spawn. (Hopefully there will be a male and female that are spawned to begin the lab. To avoid having sea urchins of all one sex have a large number of urchins on hand.) The collected gametes will them be mixed to induce fertilization.
Independent Practice:
The students will then make a wet mount slide (covered in the previous lab) of the fertilized solution and begin to identify the stages of cell division and mitosis.
At the end of the day, refrigerate the fertilized solution to preserve it for the following day.
Day 5: The students will continue to identify the phases of cell division and mitosis.
Guided Practice:
The teacher will assist students in identifying the appropriate phases by having them refer to their notes as to the characteristics of each phase. The teacher will also (if equipment is available) find the phases on a video microscope so students can see what they are supposed to be finding.
Closure:
For their conclusion of the lab students will answer this question in their lab books: Using your notes from class, explain what is happening in each stage cell division and mitosis for each picture that you drew.
Assessment:
Students will be tested on the phases and characteristics of cell division and mitosis in the form of a chapter test.
Adaptations For:
ESL: Emphasize the vocabulary and how it relates to each phase
LD: Have them draw the phases as you find them on the video microscope
GATE: When they are finished allow them to dissect the spawned specimens
Classroom Management:
Students will be reminded that their behavior in the note taking part of the unit will effect their participation in the lab portion of it.
Students will need to be reminded of how behave if they are not to lose their privileges of participating in lab. In our classes they will be issues a “Lab Safety Citation” if they choose to misbehave in lab. This results in a zero for the lab no matter how much they have done.
Paraprofessional
Management:
Aides in the classroom will assist students as they need based on their individual situations. They will bring any specific problems that they cannot address to the teacher’s attention for individual assessment.
Learning
Modalities: Auditory:
Lecture notes, Lab instructions Visual: Notes on the board, Teacher
demonstrations Kinesthetic: Creating a wet mount slide, Operation
of he microscope, Drawing cell division phases in
their notes and in lab books
Materials/Technologies:
Student microscopes
Video Microscope (if available)
25 gauge syringe
Sea urchins: Strongylocentrotus purpuratus
Or other urchin species
Beakers for catching gametes
Slides, cover slips, eye droppers
(for wet mounts)
Student Lab Books (used in our classes)