Archive for June 22, 2007
Post-Instruction Evaluation
The following day, the students will be given a quiz covering the previous day’s material.
Quiz questions:
1. Where is DNA found in the cell?
2. Do all cells have DNA?
3. Why is DNA essential to a cell?
During-Instruction Evaluation
Students will be evaluated informally during the instruction following the teacher’s prompting. As students prepare to complete each step of the laboratory procedure, asking questions such as, “Why do we need to add the salt?” “What does the hot water bath do for the enzymes that bind DNA together?”. The goal is that the students must think about each step, and the process that are occuring at a cellular level.
Also, students will make inscriptions of lab data and observations as they complete the lab exercise. A copy of these inscriptions can be collected for a formal evaluation.
Previewing Vocabulary and Concepts
The following questions will be asked before students begin the lab activity, in order to determine their understanding of DNA before the unit begins.
1. What is DNA?
2. What does DNA stand for?
3. Where is DNA found in the cell?
4. What is DNA used for by the cell?
5. What is a chromosome?
6. How many chromosomes are found in human cells?
Explanation
To explain more about DNA structure, the teacher will lead a short (10-15 minute) lecture/discussion on the finer points of DNA structure and function.
Lecture Outline
1. DNA function: “code of life”, protein production, direction of cell’s activities
2. DNA structure: double helix, chromatin, and chromosomes
Elaboration
The teacher will invite students to further explore DNA and DNA fingerprinting by researching one of the following:
1. How do forensic detectives fingerprint DNA?
2. How do scientists “get enough” DNA to conduct fingerprinting tests?
3. What is the Human genome project?
4. What is the relationship between DNA and Chromosomes?
Exploration
The students will be allowed to explore the process of extracting dna from an onion cell. This experimental procedure was modified from www.sciencebuddies.com.
Engagement
In order to spark students’ interest in DNA, and to activate some background knowledge about the subject, the teacher will read an article about DNA fingerprinting, and its role in crime-solving. One example is “From Coffee Cup to Court” by Anna Quindlen. This article is from Newsweek (4/29/02) , and follows the story of a murderer/rapist who was captured because he left his saliva (and DNA) on a coffee cup. Bonus: The article mentions possible career options that might interest students.
The article can be accessed via accessmylibrary.com:
Introduction to DNA Lesson Plan 