Grade Six Science
Answers to last week’s exercise Exercise 2
Hello Boys and Girls,
Are you doing well? Have you been doing lots of work and revising a lot? I hope that you still try to read a little bit, despite the amount of work you have to do. Have lots of fun. As you work.
For the past few weeks we found out a lot about air. Do you remember them? Call a friend and together find out how much you know about air so far.
Look below to refresh your memory.
What is air really composed of?
Yes, air is a mixture of several invisible gases.
Let us imagine that the air is made up of 100 small cubes (a). 21 of these cubes would be oxygen – 21% or 1/5.
Most of the air is nitrogen, 78 cubes – 78% (b).
Other gases make up the other 1 part – 1%.
In the 1% can be found carbon dioxide and other rare gases, such as argon and neon.
Another way of showing the different gases is by cutting up a circle to show the amounts (c). Because this is like cutting a pie it is called a pie chart.
This week we will conclude our investigation of air. We have already seen that air is all around us. There is a layer around the earth . Can you tell what that layer is called? Yes, it is the atmosphere. The atmosphere protects the Earth from harmful rays from space and from the Sun. The atmosphere is like a blanket, which stops the Earth from getting too hot or too cold.
The atmosphere presses down on the Earth. As we learnt last week, this pressing force is called air pressure. If we travel upwards through the atmosphere there is less air above us and so air pressure becomes less as we go higher. Human Beings cannot survive if the air pressure is very low. Why is this so? Find out.
What happens when we fly in aeroplanes? Aeroplanes have special cabins that keep the air pressure the same as on the ground. Exciting, isn't it? Have you ever flown in an aeroplane and felt your ears uncomfortable? Why does this happen?
Like water, air can also sometimes be made dirty and unsafe by pollution. (Do you remember this word being used when we looked at water?) Some gases and particles in the air can make it harmful for Human Beings, other animals and plants. Air pollution can come from many places. What are some of these places? Yes, some of the common places are :
• fumes from cars
• chemicals and smoke from factories
• smoke from burning rubbish • smoke from burning coal • smoke from cigarettes
if people breathe in badly polluted air it can cause diseases. Asthma and lung cancer are common diseases caused by air pollution.
It is important that we keep our air as clean as possible so that it is safe for living things to breathe.
Let’s answer a few questions.
1. What happens to air pressure as you move upward into the atmosphere? (a) increases
(b) decreases
(c) stays the same
2. A device that is used to measure atmospheric pressure is a ___________. (a) barometer
(b) thermometer
(c) kilometer
(d) micrometer
3. Which of the following statements is incorrect?
(a) All living things require air to breathe.
(b) We can feel air, but we cannot see it.
(c) Moving air makes it possible to fly a kite.
(d) Air is present everywhere but not in soil.
4. Wind does not help in the movement of which of the following?
(a) Firki
(b) Weathercock
(c) Ceiling fan
(d) Sailing yacht
5. Mountaineers carry oxygen cylinders with them because
(a) there is no oxygen on high mountains
(b) there is a deficiency of oxygen on mountains at high altitude
(c) oxygen is used for cooking
(d) oxygen keeps them warm at low temperature.
6. The components of air which are harmful to live beings are
(a) nitrogen and carbon dioxide
(b) dust and water vapour
(c) dust and smoke
(d) smoke and water vapour
7. Shalina took a lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles con tain
(a) water vapour
(b) only oxygen gas
(c) air
(d) none of these.
8. State whether the following statements are true or false. If false, correct them. (a) Plants consume oxygen for respiration.
(b) Plants produce oxygen during the process of making their own food.
(c) Air helps in the movements of sailing yachts and gliders but plays no role in the flight of birds and aeroplanes.
(d) Air does not occupy any space.
9. A list of words is given in a box. Use appropriate words to fill up the blanks in the following statements.
[Air, oxygen, wind, water vapour, mixture, combination, direction, road, bottles, cylinders]
(a) The ______ makes the windmill rotate.
(b) Air is a ______ of some gases.
(c) A weathercock shows the in which the air is moving at that place.
(d) Mountaineers carry oxygen ___ with them while climbing high mountains
10. In a number of musical instruments, air plays an important role. Can you name such instruments?
Until next time, goodbye Boys and Girls!
Exercise 3 a) 5 b) 7 c) 12 d) 56 e) 36 f) 5 g) 144 h) 9
Exercise 4
1. Josh scored 40 points. 2. Farmer Jones has 16 pigs
altogether.
3. Sadie has a total of 35 marbles.
4. Tom will walk 25 miles in a
week.
Greetings, boys and girls. Welcome back to our Math corner. How are you today? Are you prepared for school, tomorrow? I hope you are! In this week’s session, we will be examining a few concepts of ‘Sets.’ I am sure you have previously examined some basic concepts of the said topic. Let’s begin.
Sets
What is a set?
In mathematics, a set is defined as a collection of well-defined objects form ing a group. Usually, sets are represented in curly braces {}, for example, A = {1,2,3,4} is a set.
Equal and Equivalent sets
Boys and girls, do you know what equal sets are? Let’s find out!
What are equal sets?
Two sets are equal if they contain the same elements. That is; they contain the exact same elements, though not necessarily in the same order.
Example
• A: {7, 9, 11} and B: {9, 11, 7}
• A: { 1 5 , 1 4 , 1 3 , 1 2 } and B: { 1 2 , 1 3 , 1 4 , 1 5 }
In the examples above, we notice that even though the elements aren’t arranged in the same order, the sets still contain the same elements.
Let’s now move on to another type of set called ‘Equivalent set’
Equivalent sets
Two sets are equivalent if they have the same number of elements. The sets do not have to have the same elements, just the same number of elements.
Example
• Set A: {1,2,3,5,7}
• Set B: {Marvin, Neil, Alex, Mark, Andrew}
Even though Sets A and B have completely different elements (Set A comprises numbers, and Set B comprises Names) they have the same amount of elements, which is five. Set A contains five elements and Set B also contains five elements. That makes them equivalent sets!
So far, we know that, two sets are equal when they have same elements and two sets are equivalent when they have same number of elements whether the elements should be same or not.
Exercise 1
1. State, whether each pair of sets, given below are equal sets or equivalent
sets: 1. Set A {3, 5, 7} and Set B {5, 3, 7}
2. Set A {8, 6, 10, 12} and{ Set B {3, 2, 4, 6} 3. Set A {5, 2, 1, } and Set B {8, 6, 7}
4. Set A {2, 4, 6, 8, 1} and Set B{a, b, d, e, m} 5. Set A{5, 2, 2, 4} and Set B {5, 4, 2, 2}
6. Set A {Natural numbers less than five} and
Set B {Letters of the word ‘BOAT’}
7. Set A {2, 4, 6, 8, 10} and Set B {even natur
al numbers less than 12}
8. Set A {a, b, c, d} and Set B {Δ, ○, □, ∇}
Excellent work, students! Let’s now move on to another topic.
Have you ever heard the term ‘Venn Diagram’ before? If yes, write down three things you know about a Venn diagram.
The Venn diagram
What is a Venn diagram?
A Venn diagram is an illustration that uses circles to show the relationships among things or finite groups of things. Circles that overlap have elements that are common, while circles that do not overlap do not share common elements. Venn diagrams help to visually represent the similarities and differences between two concepts.
Parts of a Venn diagram
Basic Symbol associated with the Venn Diagram
There are more than 30 Venn diagram symbols. We will learn about the three most commonly used symbols in this lesson.
Example
Let us understand the concept and the usage of the three basic Venn diagram symbols using the image given below.
Set A- represents the number of students who prefer hamburger.
Set B- represents the number of students who prefer hotdogs.
Set C- represents the number of students who prefer pizza.
1. How many students joined only the math club? 2. How many students joined the arts club? 3. How many students joined a club but did not join the math or arts clubs? 4. How many students joined both the arts club and the music club? 5. How many students did not join any clubs? 6. How many students joined all the three clubs?
That’s all for today, pupils.
Thank you for being receptive. Until next week, bye!