CELERY EXPERIMENT:Primary 4 Lesson

To further recall the subject matter, it’s better to have an activity that leads them to experience theory in reality like what the Primary 4 students did. Application is very important for they see in actual situation the imaginative ideas that needs to be expressed.

Primary 4 performed celery experiment. This is to prove that water travels or circulates in every part of the plant as human body undergoes in circulatory system. The celery stalks are soaked in the colored water for a day. The next day, the stalks will be cut to see the red spots.

The plants have 2 tubes that play important role in circulation of the food and water: xylem and phloem.

Skeletal System Activity: Science Lesson of Primary 3

Let’s have a quick glance with the primary 3 students while having their Science activity. It is relevant to Skeletal system lesson. To make the retention properly registered in their mind, there must be a related activity as follow-up.

BUTTERFLY MOBILE ARTS

This one is interesting too. Students enjoyed this activity very much. After studying the life cycle of a butterfly, I asked them to bring materials to make the butterfly mobile art. This is to inculcate fully the life stage of a butterfly.

MAKING OF LUNG MACHINE: Primary 4 Science Activity

Primary 4 students are ready to experience some complicated activity that requires their skills in creating specific object. During their Science lesson, I decided to launch unusual activity like this which helps a lot in improving scientific skill the students should apply. This is related to the topic called AIR and Respiratory system.

It enables them to remember how the body acquires oxygen and even the movement or function of the parts of the body involved in respiratory system.

Circulatory System: Primary 4 Lesson

What is the job of the Circulatory System?

The Circulatory System is responsible for transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce. It is an amazing highway that travels through your entire body connecting all your body cells.

Parts of the Circulatory System
The circulatory System is divided into three major parts:

The Heart
The Blood
The Blood Vessels
The Heart

The Heart is an amazing organ. The heart beats about 3 BILLION times during an average lifetime. It is a muscle about the size of your fist. The heart is located in the center of your chest slightly to the left. It’s job is to pump your blood and keep the blood moving throughout your body.

It is your job to keep your heart healthy and there are three main things you need to remember in order to keep your heart healthy.

Exercise on a regular basis. Get outside and play. Keep that body moving (walk, jog, run, bike, skate, jump, swim).
Eat Healthy. Remember the Food Pyramid and make sure your eating your food from the bottom to top.
Don’t Smoke! Don’t Smoke! Don’t Smoke! Don’t Smoke! Don’t Smoke!

The Blood

The blood is an amazing substance that is constantly flowing through our bodies.

Your blood is pumped by your heart.
Your blood travels through thousands of miles of blood vessels right within your own body.
Your blood carries nutrients, water, oxygen and waste products to and from your body cells.
A young person has about a gallon of blood. An adult has about 5 quarts.
Your blood is not just a red liquid but rather is made up of liquids, solids and small amounts of oxygen and carbon dioxide.

Blood Cells

Red Blood Cells
Red Blood Cells are responsible for carrying oxygen and carbon dioxide. Red Blood Cells pick up oxygen in the lungs and transport it to all the body cells. After delivering the oxygen to the cells it gathers up the carbon dioxide(a waste gas produced as our cells are working) and transports carbon dioxide back to the lungs where it is removed from the body when we exhale(breath out). There are about 5,000,000 Red Blood Cells in ONE drop of blood.
White Blood Cells (Germinators)
White Blood Cells help the body fight off germs. White Blood Cells attack and destroy germs when they enter the body. When you have an infection your body will produce more White Blood Cells to help fight an infection. Sometimes our White Blood Cells need a little help and the Doctor will prescribe an antibiotic to help our White Blood Cells fight a large scale infection.
Platelets
Platelets are blood cells that help stop bleeding. When we cut ourselves we have broken a blood vessel and the blood leaks out. In order to plug up the holes where the blood is leaking from the platelets start to stick to the opening of the damaged blood vessels. As the platelets stick to the opening of the damaged vessel they attract more platelets, fibers and other blood cells to help form a plug to seal the broken blood vessel. When the platelet plug is completely formed the wound stops bleeding. We call our platelet plugs scabs.

Plasma
Plasma is the liquid part of the blood. Approximately half of your blood is made of plasma. The plasma carries the blood cells and other components throughout the body. Plasma is made in the liver.
Where are the blood cells made?
The Red Blood Cells, White Blood Cells and Platelets are made by the bone marrow. Bone marrow is a soft tissue inside of our bones that produces blood cells.

The Blood Vessels

In class we talked about three types of blood vessels:

Arteries
Capillaries
Veins

Arteries
Arteries are blood vessels that carry oxygen rich blood AWAY from the heart. Remember, A A Arteries Away, A A Arteries Away, A A Arteries Away.
Capillaries
Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances(nutrients), oxygen and wastes pass in and out of your blood through the capillary walls.
Veins
Veins carry blood back toward your heart.

AMAZING FACTS
One drop of blood contains a half a drop of plasma, 5 MILLION Red Blood Cells, 10 Thousand White Blood Cells and 250 Thousand Platelets.
You have thousands of miles of blood vessels in your body. “Bill Nye the Science Guy” claims that you could wrap your blood vessels around the equator TWICE!
Keep your heart healthy…it’s going to have to beat about 3 BILLION times during your lifetime!

Respiration and Photosynthesis

Respiration in plants
Respiration
Living cells respire. Aerobic respiration is the chemical reaction used to release energy from glucose. It is called aerobic because oxygen from the air is also needed.

Notice that the word equation for respiration is the reverse of the word equation for photosynthesis. Check back if you are not sure of this.
Plants
Plant cells respire, just as animal cells do. If they stop respiring, they will die. Remember that respiration is not the same as breathing, so take care – plants do not breathe.

Plants respire all the time, whether it is dark or light. They are always taking in oxygen and releasing carbon dioxide. But they also photosynthesise when they are in the light – and remember that plants take in carbon dioxide and release oxygen when they photosynthesise.

Photosynthesis usually results in a net food gain, once respiration has been accounted for. This means that there is an increase in the biomass of the plant.

Plants that lose their leaves in winter store food produced during the summer by photosynthesis. They store enough food to last them over winter, and to provide energy reserves for new growth in the spring.

USES OF CARBON DIOXIDE

The chemical compound carbon dioxide, or CO2, is an atmospheric gas composed of one carbon and two oxygen atoms. Carbon dioxide results from the combustion of organic matter if sufficien amounts of oxygen are present. It is also produced by various microorganisms in fermentation and is breathed out by animals. Plants take it in for their nutrition and growth, the carbon being retained and the oxygen released. It is present in the Earth’s atmosphere at a low concentration and acts as a greenhouse gas. It is a major component of the carbon cycle.

Carbon dioxide is a colorless gas with a weak odor. It is about 1.5 times as dense as air. The carbon dioxide molecule
O=C=O
contains two double bonds and has a linear shape. It has no electrical dipole. As it is fully oxidized, it is not very reactive and in particular not flammable.
Carbon dioxide can be reduced to a liquid and solid form by intense pressure. At standard pressure, it is never liquid: it directly passes between the gaseous and solid phase at -78°C in a process called sublimation.
Water will absorb its own volume of carbon dioxide, and more than this under pressure. About 1% of the dissolved carbon dioxide turns into carbonic acid, resulting in a slightly acidic taste. The carbonic acid in turn dissociates partly to form bicarbonate and carbonate ions.

Uses

Carbon dioxide in its solid frozen form it is also known as dry ice. It is used
for cooling
to produce ‘dry ice fog’ for special effects: when dry ice is put into contact with water, the resulting mixture of CO2 and cold humid air causes condensation and a fog
for cleaning: shooting tiny dry ice pellets at a surface cools the dirt and causes it to pop off
Dry ice is produced by compressing CO2 to a liquid form, removing excess heat, and then letting the liquid carbon dioxide expand quickly. This expansion causes a drop in temperature so that some of the CO2 freezes to “snow” which is then compressed.
Carbon dioxide extinguishes flames, and some fire extinguishers[?] contain pressured liquid carbon dioxide. Life jackets[?] often contain capsules of pressured liquid carbon dioxide used for quick inflation.
Water containing dissolved carbon dioxide is also known as carbonated water or soda water. Carbonated water is contained in many soft drinks and some natural springs. Some beverages, such as beer and sparkling wine contain carbon dioxide as a result of fermentation.
Many leavening agents used for baking produce carbon dioxide to cause the dough to rise. Examples are baker’s yeast and baking powder.
Biology
Carbon dioxide is a waste product in organisms that obtain energy from breaking down sugars or fats with oxygen as part of their metabolism, in a process known as cellular respiration. This includes all animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood (where most of it is held in solution) from the body’s tissues to the lungs where it is exhaled.
Carbon dioxide, when breathed in high concentrations (about 5% by volume), is toxic to humans and other animals. Hemoglobin, the main molecule in red blood cells, can bind both to oxygen and to carbon dioxide. If the CO2 concentration is too high, then all hemoglobin is saturated with carbon dioxide and no oxygen transport takes place (even if plenty of oxygen is in the air). Carbon dioxide and dry ice should therefore only be handled in well ventilated areas.
Plants remove carbon dioxide from the atmosphere by photosynthesis, which uses light energy to produce organic plant materials by combining carbon dioxide and water. This releases free oxygen gas. Sometimes carbon dioxide gas is pumped into greenhouses to promote plant growth.
Atmosphere
Despite its low concentration of about 0.037% or 370 ppm by volume, CO2 is a very important component of Earth’s atmosphere, because it traps infrared radiation and thus participates in the greenhouse effect. Atmospheric CO2 has increased about 30 percent since the early 1800s, with an estimated increase of 17 percent since 1958 (burning fossil fuels such as coal and petroleum is the leading cause of increased CO2, deforestation the second major cause).
The increased amounts of CO2 in the atmosphere are widely believed to enhance the greenhouse effect and thus contribute to global warming; this has led to international agreements such as the Kyoto Protocol which aim to limit the release of CO2 into the atmosphere. Some have proposed carbon sequestration as a method to reduce the concentration (or at least slow the rate of increase) of human-made CO2 from entering the atmosphere.
Carbon dioxide is the main component of the atmospheres of Mars and Venus.
Oceans
The Earth’s oceans dissolve a major amount of carbon dioxide. The resulting carbonate anions bind to cations present in sea water such as Ca2+ and Mg2+ to form deposits of limestone and dolomite.
History
Carbon dioxide was first described in the 17th century by the Belgian chemist Jan Baptist van Helmont[?].

Function of Stomata: P4 lesson

What are stomata?

Figure 1: Stomata of Tall fescue grasses.
Stomata are tiny plant structures found on the outer skin layer, also known as the epidermis, of plants (Figure 1). They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. The word stomata means “mouth” in Greek because they allow communication between the internal and external environments of the plant. Their main function is to allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out of the leaf. Stomata are found on all above-ground parts of plants including the petals of flowers, petioles, soft herbaceous stems and leaves. They are formed during the initial stages of the development of these various plant organs and therefore reflect the environmental conditions under which they grew.
Stomatal density, size and shape
Stomatal density refers to the number of stomata per squared millimeter. Typical densities can vary from 100 to 1000 depending on the plant species and the environmental conditions during development. More stomata are made on plant surfaces under higher light, lower atmospheric carbon dioxide concentrations and moist environments. Grasses typically have lower stomatal densities than deciduous trees. The size and shape of stomata also vary with different plant species and environmental conditions. For example, grasses have guard cells that resemble slender dumbbells whereas trees and shrubs have guard cells that resemble kidney beans.
Physiological function of stomata
Leaves are the main “food manufacturing” organs of plants. They make food from carbon dioxide and water in the presence of light during a process called photosynthesis. As stomata open in the presence of light, carbon dioxide will diffuse into the leaf as it is converted to sugars through photosynthesis inside the leaf. At the same time, water vapor will exit the leaf along a diffusive gradient through the stomata to the surrounding atmosphere through the process of transpiration. Consequently, plants face the dilemma of taking up carbon dioxide while losing water vapor through their stomata. If this water loss remains unchecked, they can deplete their water reserve. This depletion can become catastrophic to the physiological functioning of the plant given that is the most essential solvent in which biochemical and growth processes occur. Based on Darwinian principles, it is presumed that selective adaptation has driven plants to acquire characteristics which enable them to grow more quickly without diminishing the probability of survival. If plants have not acquired the characteristics to withstand changes in water availability in their growth environment, plants may exacerbate their water shortage by not regulating the size of their stomatal apertures in an optimal manner and may fail to survive when water availability declines.
Optimal size of stomatal apertures
The Optimisation Theory, first proposed by Ian Cowan and Graham Farquhar (1977) suggests that the gas exchange of a plant is optimal if the plant is maximizing photosynthesis at a given average rate of transpiration. This ratio of photosynthesis to transpiration defines the instantaneous water-use efficiency (WUE) of the plant. The WUE of the leaf, when compared to economic principles, can be considered to be analogous to the interest rate on an invested resource. The invested resource in this case is water transpired, while the interest is the carbon gained through photosynthesis. The optimal stomatal aperture size is one in which the interest rate, WUE, is maximized as the environmental conditions change.
Stomatal apertures will typically vary in response to changes in light intensity, saturation deficit of ambient water vapor and soil moisture availability. As stomatal aperture size changes, rates of photosynthesis and transpiration will vary because the pore size will provide a corresponding resistance to the diffusion of CO2 into and H2O out of the leaf. The inverse of this resistance can be calculated as the conductance to these two gases across a leaf surface.
Stomatal conductance
Plant biologists typically measure stomatal conductance using a specialized instrument called an IRGA (Infra Red Gas Analyzer).

Figure2: Leaf chamber attached to Infra red gas analyzer connected to computer console
This instrument allows one to clamp a leaf into a chamber and the relative mole fractions of CO2 and water vapor entering and leaving the chamber are monitored over time. The leaf touches a temperature thermocouple inside the chamber so that leaf temparature can be monitored in conjunction with air temperature that exits the chamber. The leaf temperature is used to determine the saturated molar concentration of water vapor inside the leaf intercellular air spaces. The resistance to the diffusion of water vapor from inside the leaf to the air stream passing over the leaf is calculated from the difference between the molar concentrations of saturated water vapor inside the leaf air spaces in the air stream passing over the leaf. The resistance will increase as the stomatal aperture size decreases. The stomatal conductance to water vapor decreases as the resistance increases. Because H2O has a lighter molecular mass than CO2, water typically diffuses 1.6 times faster than CO2. The conductance to CO2 into a leaf is going to be 0.625 times the conductance to H2O out of the leaf.
As stomatal conductance declines, WUE will increase if the reduction in photosynthesis is lower than the reduction in transpiration. Plant species typically show this physiological response under mild drought stress. Under severe drought stress, the photosynthetic biochemical machinery can become damaged. As a result, WUE will decrease as stomatal conductance declines if the reduction in photosynthesis becomes larger than the reduction in transpiration.

Who invented the battery?

The first battery was invented in 1800 by Alessandro Volta. Although it was of great value for experimental purposes, its limitations made it impractical for large current drain. Later batteries, starting with John Frederic Daniell’s wet cell in 1836, provided more reliable currents and were adopted by industry for use in stationary devices, particularly in telegraph networks where, in the days before electrical distribution networks, they were the only practical source of electricity.[1] These so-called wet cells used liquid electrolytes, and were thus prone to leaks and spillage if not handled correctly. Some, like the gravity cell, could only function in a certain orientation. Many used glass jars to hold their components, which made them fragile. These practical flaws made them unsuitable for portable appliances. Near the end of the 19th century, the invention of dry cell batteries, which replaced liquid electrolyte with a paste, made portable electrical devices practical.

Respiratory System: My lesson today in Primary 4

Anatomy and Function of the Normal Lung

To understand your lung condition, you should be familiar with how the lungs normally work.

How do the lungs normally work?

The chest contains two lungs, one lung on the right side of the chest, the other on the left side of the chest. Each lung is made up of sections called lobes. The lung is soft and protected by the ribcage. The purposes of the lungs are to bring oxygen (abbreviated O2), into the body and to remove carbon dioxide (abbreviated CO2). Oxygen is a gas that provides us energy while carbon dioxide is a waste product or “exhaust” of the body.

How do the lungs protect themselves?

The lungs have several ways of protecting themselves from irritants. First, the nose acts as a filter when breathing in, preventing large particles of pollutants from entering the lungs. If an irritant does enter the lung, it will get stuck in a thin layer of mucus (also called sputum or phlegm) that lines the inside of the breathing tubes. An average of 3 ounces of mucus are secreted onto the lining of these breathing tubes every day. This mucus is “swept up” toward the mouth by little hairs called cilia that line the breathing tubes. Cilia move mucus from the lungs upward toward the throat to the epiglottis. The epiglottis is the gate, which opens allowing the mucus to be swallowed. This occurs without us even thinking about it. Spitting up sputum is not “normal” and does not occur unless the individual has chronic bronchitis or there is an infection, such as a chest cold, pneumonia or an exacerbation of chronic obstructive pulmonary disease (COPD).

Another protective mechanism for the lungs is the cough. A cough, while a common event, is also not a normal event and is the result of irritation to the bronchial tubes. A cough can expel mucus from the lungs faster than cilia.

The last of the common methods used by the lungs to protect themselves can also create problems. The airways in the lungs are surrounded by bands of muscle. When the lungs are irritated, these muscle bands can tighten, making the breathing tube narrower as the lungs try to keep the irritant out. The rapid tightening of these muscles is called bronchospasm. Some lungs are very sensitive to irritants. Bronchospams may cause serious problems for people with COPD and they are often a major problem for those with asthma, because it is more difficult to breathe through narrowed airways.

How does air get into the body?

To deliver oxygen to the body, air is breathed in through the nose, mouth or both. The nose is the preferred route since it is a better filter than the mouth. The nose decreases the amount of irritants delivered to the lung, whilst also heating and adding moisture (humidity) into the air we breathe. When large amounts of air are needed, the nose is not the most efficient way of getting air into the lungs and therefore mouth breathing may be used. Mouth breathing is commonly needed when exercising.

After entering the nose or mouth, air travels down the trachea or “windpipe”. The trachea is the tube lying closest to the neck. Behind the trachea is the esophagus or “food tube”. When we inhale air moves down the trachea and when we eat food moves down the esophagus. The path air and food take is controlled by the epiglottis, a gate that prevents food from entering the trachea. Occasionally, food or liquid may enter the trachea resulting in choking and coughing spasms.

The trachea divides into one left and one right breathing tube, and these are termed bronchi. The left bronchus leads to the left lung and the right bronchus leads to the right lung. These breathing tubes continue to divide into smaller and smaller tubes called bronchioles. The bronchioles end in tiny air sacs called alveoli. Alveoli, which means “bunch of grapes” in Italian, look like clusters of grapes attached to tiny breathing tubes. There are over 300 million alveoli in normal lungs. If the alveoli were opened and laid out flat, they would cover the area of a doubles tennis court. Not all alveoli are in use at one time, so that the lung has many to spare in the event of damage from disease, infection or surgery.

Which muscles help in the breathing process?

Many different muscles are used in breathing. The largest and most efficient muscle is the diaphragm. The diaphragm is a large muscle that lies under the lungs and separates them from the organs below, such as the stomach, intestines, liver, etc. As the diaphragm moves down or flattens, the ribs flare outward, the lungs expand and air is drawn in. This process is called inhalation or inspiration. As the diaphragm relaxes, air leaves the lungs and they spring back to their original position. This is called exhalation or expiration. The lungs, like balloons, require energy to blow up but no energy is needed to get air out.

The other muscles used in breathing are located between the ribs and certain muscles extending from the neck to the upper ribs. The diaphragm, muscles between the ribs and one of the muscles in the neck called the scalene muscle are involved in almost every breath we take. If we need more help expanding our lungs, we “recruit” other muscles in the neck and shoulders. In some conditions, such as emphysema, the diaphragm is pushed down so that it no longer works properly. This means that the other muscles must work extra hard because they aren’t as efficient as the diaphragm. When this happens, patients may experience breathlessness or shortness of breath.