notebook-lesson_science_subject_in_educa

Image Formation by Ray Diagrams and the Mirror Equation

Ray Diagrams

Ray diagrams are visual representations of how light rays interact with mirrors. They use a few simple rules to trace the path of light and determine the location, size, and orientation of the image.

Rules for Ray Diagrams:

1. Ray parallel to the principal axis: After reflection, this ray passes through the focal point (F) of the mirror.
2. Ray passing through the focal point (F): After reflection, this ray becomes parallel to the principal axis.
3. Ray passing through the center of curvature (C): This ray reflects back on itself.

Types of Mirrors:

- Concave Mirror: A converging mirror that can form both real and virtual images.
- Convex Mirror: A diverging mirror that always forms virtual images.

Image Characteristics:

- Real: The image is formed by actual intersection of light rays. It can be projected onto a screen.
- Virtual: The image is formed by the apparent intersection of light rays, not actual intersection. It cannot be projected onto a screen.
- Upright: The image is oriented the same way as the object.
- Inverted: The image is oriented upside down compared to the object.
- Magnified: The image is larger than the object.
- Minified: The image is smaller than the object.

The Mirror Equation

The mirror equation mathematically relates the object distance (u), image distance (v), and focal length (f) of a mirror:

Where:

- f: Focal length of the mirror (positive for concave, negative for convex)
- u: Object distance (always positive)
- v: Image distance (positive for real images, negative for virtual images)

Magnification

Magnification (M) describes the ratio of image height (h') to object height (h):


- M > 1: Magnified image
- M 0: Upright image
- M < 0: Inverted image

Applications of Mirror Equation and Ray Diagrams

- Designing optical instruments: Understanding how mirrors form images helps in designing telescopes, microscopes, and other optical instruments.
- Understanding human eye: The human eye uses a lens (similar to a curved mirror) to focus light on the retina.
- Solar energy: Parabolic mirrors are used to concentrate sunlight and generate heat.

Examples

1. Concave Mirror:

- Object at infinity: The image is formed at the focal point (F), real, inverted, and highly minified.
- Object beyond the center of curvature (C): The image is formed between F and C, real, inverted, and minified.
- Object at the center of curvature (C): The image is formed at C, real, inverted, and the same size as the object.
- Object between C and F: The image is formed beyond C, real, inverted, and magnified.
- Object at the focal point (F): No image is formed.
- Object between F and the mirror: The image is formed behind the mirror, virtual, upright, and magnified.

2. Convex Mirror:

- Object at any distance: The image is always virtual, upright, and minified, formed behind the mirror. Ands that must be helpful in stud

1. Distinguishing And Constructing Various Paper-and-Pencil-Test

2. LEARNING OUTCOMES: 1. Construct a Table of Specifications 2. Construct paper-and- pencil tests in accordance with the guidelines in test construction.

3. Introduction In this Chapter we are concerned with developing paper-and- paper tests for assessing the attainment of educational objectives based on Bloom’s taxonomy. Paper-and-pencil test can either be selected response or constructed-response types. Selected response type includes (a) true-false items, (b) multiple-choice type items and (c)matching type. Constructed-response type of test includes (a) enumeration, (b) completion and (c.) essays.
The construction of valid test items begins with a Table of Specifications.

4. 5.1 Planning a Test and Construction of Table of Specifications (TOS) The important steps in planning for a test are: ✓ Identifying test objectives/lesson outcomes ✓ Deciding on the type of objective test to be prepared ✓ Preparing a Table of Specifications (TOS) ✓ Constructing the draft test items ✓ Try-out and validation

5. Identifying Test Objectives An objective test, if it is to be comprehensive, must cover the various levels of Bloom’s taxonomy. Each objective consists of a statement of what is to be achieved preferably by the students.

6. The students must be able identify the subject and the verb in a given sentence students must be able to write sentences observing rules on subject-verb agreement Analysis/Analyzing The students must be able to break down a given sentence into its subject and predicate Evaluation/Evaluating The students must be able to evaluate whether or not a sentence observes rules on subject-verb agreement The students must be able to determine the appropriate form of a verb to be used given the subject of a sentence. Knowledge/Remembering Comprehension/Understanding Application/Applying Synthesis/Creating The students must be able to formulate rules to be followed regarding subject-verb agreement

7. Deciding On the type of objective test The test objectives guide the kind of objective tests that will be designed and constructed by the teacher. This means aligning the test with the lesson objective/outcome. Example : For the first four (4) levels, we may want to construct a multiple-choice type of test while for application and judgment, we may opt to give an essay test or a modified essay test.At all times, the test to be formulated must be aligned with the learning outcome. This is the principle of constructive alignment.

8. PREPARING A TABLE OF SPECIFICATIONS (TOS) Table of Specifications (TOS) is a test map that guides the teacher in constructing a test. The TOS ensures that there is balance between items that test lower level thinking skills and those which test higher order thinking skills (or alternatively, a balance between easy and difficult items) in the test.The simplest TOS consists of:-four (4) columnslevel of objective to be tested--statement of objective-item numbers where such an objective is beingtested -number of items and percentage out of the total for that particular objective Without the TOS, the tendency for the test maker is to focus too much on facts and concepts at the Recall level.

9. CONSTRUCTING THE TEST ITEMS As a general rule, it is advised that the actual number of items. to be constructed in the draft should be double the desired number of items Example:If there are five (5) recall level items to be included in the final test form, then at least ten (10) recall level items should be included in the draft.The subsequent test try-out and item analysis will most likely eliminate many of the constructed items in the draft (either they are too difficult, too easy or non-discriminatory), hence it will be necessary to construct more items than will actually be included in the final test form.

10. ITEM ANALYSIS AND TRY-OUT The test draft is tried out to a group of pupils or students. The purpose of this try-out is to determine the:1. item characteristics through item analysis2. characteristics of the test itself-validity, reliability and practicality.

11. Types of Paper-and-Pencil Test Development of paper-and-pencil tests requires careful planning and expertise in terms of actual test construction. The more seasoned teachers can produce true-false items that can test even higher order thinking skills and not just rote memory learning. Essays are easier to construct than the other types of objective test, but the difficulty in scoring essay examinations teachers from using this particular form of examination in actual practice.

12. Constructing Selected-Response Type True-False Test It is best that the teacher ensures that a true-false item is able to discriminate properly between those who know and those who are just guessing. A modified true-false test can offset the effect of guessing by requiring students to explain their answer and to disregard a correct answer if the explanation is incorrect.

13. GUIDELINES FOR CONSTRUCTING ALTERNATED-RESPONSE TEST RULE 1. Do not give a hint (inadvertently) in the body of the question. RULE 2. Avoid using the words "always," "never," "often" and other words that tend to be either always true or always false. RULE 3. Avoid long sentences as these tend to be “true.” Keep sentences short.

14. GUIDELINES FOR CONSTRUCTING ALTERNATED-RESPONSE TEST RULE 4. Avoid trick statements with some minor misleading word or spelling anomaly, misplaced phrases, etc. A wise student who does not know the subject matter may detect this strategy and this get the answer correctly. RULE 5. Avoid quoting verbatim from reference materials or textbooks. This practice sends the wrong signal to the students that is is necessary to memorize the textbook word for word and, thus, acquisition of higher level thinking skills is not given due importance.

15. RULE 6. Avoid specific determiners or give-away qualifiers. Students quickly learn that strongly worded statements are more likely to be false than true. Moderately worded statements are more likely to be true than false. Statements that are moderately worded use "many," "often," "sometime," "generally," "frequently" or "some" usually should be avoided. The statement tends to be correct. The word "usually" leads to theanswer .

16. GUIDELINES FOR CONSTRUCTING ALTERNATED-RESPONSE TEST RULE 7. With true of false questions, avoid grossly disproportionate number of either true or false statements or even patterns in the occurrence of true or false statements. RULE 8. Avoid double negatives. This makes test item unclear and definitely will confuse the student.