TEMAS OCTAVO GRADO PARA EL EXAMEN BIMESTRAL DEL PRIMERO DE JUNIO

WAVES- Preguntas partes de las ondas, tipos de ondas: transverse vs. mechanical, luz vs. sonido, velocidad de las ondas, preguntas sobre frecuencia y las diferencias en la velocidad en diferentes medios (por donde viaja la luz más rápido?) Refraction, Reflection, Diffraction.Concept of incident ray, reflecting ray, normal line, incident angle and reflecting angle.

REPRODUCTION FUNGI- Definición de hongos, usos de hongos, diferencias entre células de hongos y las células de plantas. Ventajas de reproducción asexual sobre reproducción sexual.

REPRODUCTION CELLS (MITOSIS) - preguntas sobre las diferentes fases de mitosis y los eventos que ocurren en cada una de ellas. Tipos de células en las cuales ocurren mitosis y meiosis.

REPRODUCTION PLANTS- Maneras en que las plantas se reproducen. Flores perfectas vs. Flores imperfectas. Coniferos.

Debido a que tuvo menos tiempo, 8D no tendrá que responders preguntas sobre fungi.

TEMAS SEXTO GRADO PARA EL EXAMEN BIMESTRAL DEL PRIMERO DE JUNIO

FORCE- Preguntas sobre la ecuación que se utiliza para resolver problemas de fuerza.  También habrán algunos problemas en los que se les da valores de masa y aceleración a estudiantes. Estos, tendrán que ponerlos en la ecuación y obtener la respuesta poniendo las unidades correctas (Newtons).

TORQUE - Igualmente habrán preguntas sobre la ecuación que se utiliza para hacer problemas de torque. Los estudiantes obtendrán valores de radio y fuerza; estos valores serán utilizados para obtener la respuesta de torque con las unidades correspondientes (Joules).

SIMPLE MACHINES- Problemas identificando las diferentes clases de máquinas simples. Habrán preguntas sobre las partes de palancas y ejemplos de los diferentes tipos de palancas. Se les pedirá a los estudiantes diferenciar entre la primera, segunda y tercera clase de palancas. Preguntas sobre los diferentes tipos de poleas.

MACROMOLECULES AND ELECTROLYTES- Preguntas incluirán los diferentes tipos de electrolitos.  Habrán preguntas sobre la composición del agua y de su propiedad polar vs la propiedad no polar del aceite. Composición del agua y de la sal

ORGANIC COMPOUNDS- Identificación de compuestos orgánicos e inorgánicos. Definiciones de macro, micro, hidrofílico e hidrofóbico.

PREGUNTAS DE REPASO- Preguntas sobre las diferentes subpartículas del átomo, identificando cuales son positivas, negativas y neutras.

KINGDOMS- La última pregunta del exámen le pedirá a los estudiantes que pongan información como el habitat, la nutrición y la reproducción de tres organismos. Los estudiantes podrán utilizar sus fichas bibliográficas durante el exámen para responder esta pregunta.

Atención Estudiantes Octavo Grado para esta semana

Esta semana no tendrán quiz, pero sí tendrán la siguiente actividad:

Curso 8C, debido a que tendrán salida para el 17 de Mayo al Jardín Botánico, solo tendrán una clase (2 horas de preparación para esta actividad).

Cell Reproduction Activity

Goal: To recreate the steps of mitosis and correctly label the part of the cell involved in that process.

Materials:

-          One or two sheets of paper (where you will put the different mitosis steps)

-          Pen and markers (to write information)

-          Play d oh (5 or 6 different colors)

Number of group members: maximum 2 people

Due Date:           8C— Thursday, May 19^th, 2011

                               8D—Friday, May 20^th, 2011

Instructions:

In one or two sheets of paper, and using play-d oh, you will describe and illustrate the different steps of mitosis.

Title: MITOSIS: Cell Division (2 points)

Names of the 4 steps of mitosis (4 points)

Two facts about each step in mitosis (8 points)

Correct and clear labeling of the cell at each of the steps (12 points, 3 points at each step)

Neatness (6 points)

Labeling at top right corner with full name(s), date and course number (3 points)

Total number of points: 35

Tips:

You will only have 40 minutes to work on this assignment, it´s important that you work fast and efficiently.

Assign tasks if you are working with someone else.

You can label information (title, phases, facts, identification information) before coming to class.

Only use play d oh to illustrate parts of the cell, do not spell out anything with it, it would take too long!

Eighth Grade Activity: Cell Reprodcution

Cell Reproduction

Cell reproduction is the process by which a cell divides to form two or more daughter cells.  Each daughter cell will have its own genetic material.  Cell reproduction in human cells and most cells in nature including bacteria and plants takes place through either mitosis or meiosis.

Mitosis is the main reproduction process for most cells. In humans, there are 2 main types of cells: Somatic Cells (hair cell, skin cell, liver cell, stomach cell, bone cell, blood cell, etc.-anything not a sex cell) and sex cells (sperm cells and ova). Somatic cells divide by a process called mitosis. Sex cells divide by meiosis.

The Cell Cycle

When cells are not dividing, they are carrying out their normal processes; this is, a skin cell is providing protection or producing melanin, a stomach cell is producing acid, pesin or bicarbonate, a white blood cell is fighting foreign invading agents.

When cells are not dividing, they are in a stage called interphase. Interphase is made up of 3 stages: G1 phase, S phase and the G2 phase. By the end of interphase (G2 phase), cells are ready to divide and undergo processes of mitosis and cytokinesis.

Usually, when a cell divides, both its nucleus and its cytoplasm divide in two to provide enough material to each of the daughter cells produced. The process of nuclear division into two nuclei is called mitosis. The process of cytoplasm division into two is called cytokinesis. 

Mitosis

There are four main phases in mitosis, they are Prophase, Metaphase, Anaphase and Telophase, in that order.

                                                             

Mitosis Questions

In your notes, copy the questions and answer them.

1.      1.  Draw and describe what happens in each of the phases of mitosis.

2.       2. Define cell reproduction.

3.       3. What are the 2 main types of cells in humans?

4.       4. Provide 2 examples for somatic cells and 2 examples for sex cells.

5.       5. What is the process by which somatic cells reproduce?

6.       6. What is the process by which sex cells divide?

7.       7. What is interphase?

8.       8. What happens during each of the phases of interphase? (see figure)

9.       9. What is cytokinesis?

1010.   During which phase of mitosis, do the centrioles pull apart the chromosomes?

Eighth Grade Activity:Waves and Waves Activity

WAVES

A Wave is a transfer of energy, in the form of a disturbance through some medium, without translocation of the medium. A wave having a short duration is called a pulse. Waves that vibrate in repeating cycles illustrate periodic motion or harmonic motion. One complete oscillation is called a cycle.

The first three examples are in simple harmonic motion:

TYPES OF VIBRATION

Transverse vibration occurs when vibration of the medium is perpendicular to the direction of energy transfer. The maximum and minimum positions on a transverse wave are called the crest and trough.

  

The direction of the wave is from left to right (green line) but the oscillation occurs up and down.

Longitudinal vibration occurs when the medium vibrates parallel to the direction of energy transfer. Longitudinal vibrations consist of regions of compression and refraction.

The direction of the wave is from left to right (green line) and the oscillations occur from left to right also.

Frequency (f) describes the number of cycles occurring in a given unit of time. The SI unit for frequency is hertz (Hz). The units cycles / second are also used.

Frequency = Number of cycles / Time Interval

Period (T) is the time required to complete one full cycle.

Period and frequency exhibit a reciprocal relationship.

The Amplitude (A) of a wave is the maximum displacement from the equilibrium or the rest position.

Wavelength (l) is the distance between successive crests or successive troughs. The wavelength is the shortest distance between two points in phase (or two points that have identical characteristics).

The universal wave equation (v = fl) is said to be universal because it applies to all types of waves. The universal wave equation can be used to solve various problems relating to wave motion.

PROPERTIES OF WAVES

Reflection of Waves. When a series of waves strikes a surface, the waves are reflected. Waves falling upon the barrier are called incident waves and waves reflecting from the barrier are called reflected waves. Reflection of waves can be summarized in the following law of reflection: the angle of incidence (q_i) is equal to angle of reflection (q_r). Here is a diagram illustrating the reflection of waves:

Refraction of Waves. Refraction occurs at the boundary between two different media and causes the waves to change direction as shown in the following diagram:

Diffraction of Waves. Diffraction is the bending that occurs when a wave passes around the edge of an obstacle. Waves having longer wavelengths are diffracted more than those with shorter wavelengths. When waves pass through a slit, diffraction is maximized when the wavelength and the slit width are within the same order of magnitude.

In the figure above the waves are coming from the left, they hit a barrier (in red).  Those waves passing the slit will create patterns depending on the wavelength.

LAWS OF REFLECTION

A light ray is a stream of light with the smallest possible cross-sectional area. (Rays are theoretical constructs.) The incident ray is defined as a ray approaching a surface. The point of incidence is where the incident ray strikes a surface. The normal is a construction line drawn perpendicular to the surface at the point of incidence. The reflected ray is the portion of the incident ray that leaves the surface at the point of incidence. The angle of incidence is the angle between the incident ray and the normal. The angle of reflection is the angle between the normal and the reflected ray.

The Laws of reflection:

   - The angle of incidence is equal to the angle of reflection
   - The incident ray, the normal, and the reflected ray are coplanar

Specular reflection (regular reflection) occurs when incident parallel rays are also reflected parallel from a smooth surface.

If the surface is rough (on a microscopic level), parallel incident rays are no longer parallel when reflected. This results in diffuse reflection (irregular reflection). The laws of reflection apply to diffuse reflection. The irregular surface can be considered to be made up of a large number of small planar reflecting surfaces positioned at slightly different angles. Indirect (or diffuse) lighting produces soft shadows. It produces less eye strain than harsher, direct lighting.

WAVES CLASS ACTIVITY

Answer the following questions using the reading about waves.

1.       What is a wave?

2.        

a.       What are the two main types of vibration?

b.      Write the definition for both types of vibration.

3.       Define the following terms:

a.       Frequency

b.      Period

c.       Amplitude

d.      Wavelength

4.       Make a drawing where you show the following terms: incident wave, reflected wave, angle of incidence, angle of reflection, reflecting surface, normal or perpendicular line.

5.       What does the law of reflection say?

6.       Make a drawing showing refraction of light.

7.       What is diffraction of light?

8.       What is specular or regular reflection?

9.       What is diffuse or irregular reflection?

Eighth Grade Activity: Waving

WAVING ACTIVITY

IN YOUR NOTES, DO THE FOLLOWING ACTIVITY:

·         GET IN GROUPS OF 3 PEOPLE

·         TAKE OFF 2 OR 3 SHOELACES AND TIE THEM UP END TO END.

·         HAVE 2 PEOPLE HOLD THE SHOELACES AND DEMONSTRATE HOW TO CREATE WAVES BY SHAKING YOUR HAND

1. IN YOUR NOTES, MAKE A DRAWING OF THE WAVES YOU CREATED AND LABEL THE FOLLOWING CONCEPTS

A. CREST

B. TROUGH (VALLEY)

C. AMPLITUDE

D. WAVELENGTH

2. CREATE WAVES OF LOW FREQUENCY AND HIGH FREQUENCY. MAKE A DRAWING OF THESE WAVES IN YOUR NOTES.

3. MAKE A DRAWING OF THE ELECTROMAGNETIC SPECTRUM

Sixth Grade Assignment: Simple Machines Activity

Using the Science CD, go to Menu, Second Bimester, Simple Machines, Simple Machines and then click on activity. For the first 5 problems, write the sentence and answer true or false. For the next few problems, write the question and select the correct answer.

Sixth Grade Assignment: Levers Activity

LEVERS ACTIVITY

You can use the CD to get this information (Go to Menu- Second Bimester, Simple Machines, Simple Machines).

1.       1. What are the 4 main types of simple machines?

2.      2.  Make a drawing for each of the 4 simple machines.

3.      3.  What are the main parts of a lever?

4.      4.  Make a drawing of the main parts of a lever.

5.     5.   Describe the types of levers and make a drawing for each of them.

6.      6.  Provide two examples for each type of lever.

7.       Then, on a piece of blog paper, compare your idea to a simple drawing of levers and identify where the input force, the output force and the fulcrum are located.

Sixth Grade Assignment: Torque Activity

TORQUE

What is Torque?

Torque is more than just a force which is responsible for an object to rotate, it is more of a twist.

Let us take the simplest example to understand this concept. When you push a door applying force to the edge of the door, it is simpler to push. However, if you try pushing the same door somewhere in between the edge and the axis or closer to the pivot, it becomes that much more difficult. It is because of torque. Torque depends not just on the force but also on the distance of the application of force from the pivot point. This distance is called as the moment arm and is denoted by 'r'.

With this information in hand, let us understand the torque equation.

Torque Equation

Torque is the cross product or the vector product of the distance vector 'r' and the force vector 'F'. Torque is denoted by the Greek letter 'τ' called tau. Therefore,

τ = r × F

The direction of the torque vector can be determined using the right hand rule. When we put our fingers in the direction of r, and curl them to the direction of F, then the thumb points in the direction of the torque vector. From this torque equation, we can identify that if you apply a force at the pivot of the door or in the direction of the distance vector, the torque produced will be zero and hence the door will be unmoved. The SI unit of torque is Newton-meter, which is the same as for energy (though it is called joule).

EXAMPLE PROBLEM ON TORQUE: The Swinging Door

Question
In a hurry to catch a cab, you rush through a frictionless swinging door and onto the sidewalk. The force you extered on the door was 50N, applied perpendicular to the plane of the door. The door is 1.0m wide. Assuming that you pushed the door at its edge, what was the torque on the swinging door (taking the hinge as the pivot point)?

Hints
 
 

1. Where is the pivot point?
2. What was the force applied?
3. How far from the pivot point was the force applied?
4. What was the angle between the door and the direction of force?

Solution

The pivot point is at the hinges of the door, opposite to where you were pushing the door. The force you used was 50N, at a distance 1.0m from the pivot point. You hit the door perpendicular to its plane, so the angle between the door and the direction of force was 90 degrees. Since  = r x F

Figure 1 Diagram of Example Problem 1

then the torque on the door was:

= (1.0m) (50N)
= 50 N m = 50 Joules = 50J

Note that this is only the magnitude of the torque; to complete the answer, we need to find the direction of torque. Using the right hand rule, we see that the direction of torque is out of the screen.

Practice Problems

1.      If you apply 10 Newtons of Force to open a gate that is 5 meters wide, what is the torque that you apply on that gate?

2.      If you apply 20 Newtons of Force to open that same gate, what is the torque that you apply on that gate?

3.      If you apply 10 Newtons of Force but try to open that door only 1 meter away from the pivot point, what is the torque you apply on that gate?

4.      If you apply 40 Newtons to a nut using a wrench, and the wrench is 0.2 meters long, what would be the torque you apply to that nut?

Extra Credit Problem

If you know that the torque you apply to open and big industrial nut is 10,000 Joules and the force that you applied was 500 Newtons, what is the length of the wrench you used?

Sixth Grade Assignment: Force Activity

ASSIGNMENT: PROBLEMS WITH FORCE

In the problems below, find the Force.

Use F = m x a

Look at the practice problems below to guide your work.

Examples:

A.    If a car weighs 1000 Kg and has an acceleration of 10 m/s², what is the force of that car?

F = m x a

F = (1000 Kg)x(10m/s²)

F = 10,000 Kg x m/s²

F = 10,000 Newtons (N)

Answer: The force on that car will be 10,000 Newtons.

B.     If a bowling ball weighs 12 Kg and somebody throws it with an acceleration of 2 meters per second squared, what is the force of the bowling ball?

F = m x a

F = (12 Kg)x(2 m/s²)

F = 24 Kg x m/s²

F = 24 Newtons (N)

Exercises

1. If a basketball player shoots a basketball that weighs 1 kg, with an acceleration of 3 meters per second squared, what would be its Force?

2. An Olympic athlete throws a hammer with an acceleration of 12 meters per second squared. If the hammer weighs 2 kg, with what force does the athlete throw the hammer?

3. A tennis player hits a tennis ball that weighs 0.2 Kg with an acceleration of 16 meters per second squared, with what force did the tennis player hit the tennis ball?

4. If a ping-pong player hits a ping-pong ball with an acceleration of 14 meters per second squared, and the ball weighs .005 Kg, with what force did the player hit the ball?

Extra Credit Problem: If a space rocket weighs 2,500Kg and at the moment of launch, the acceleration of the rocket is of 50 meters per second squared, what is the Force on the rocket?