Mathematics 2
Classwork № 21
Exercise 1:
Easy
Difficult
24- March 2013
Interesting
Boring
A. Point O splits the straight line AB into two parts. What does each line remind you of?
What makes each of these parts different from a straight line or from a line segment?
A
O
B
B. Label with a color pencil the origin of each ray. How is it the first ray denoted? Can
you swap the letters and why? Denote the other two rays using letters.
A
C
N
M
CK
D
K
C. Match the names with the appropriate drawings and connect them with lines.
Straight line AB
Segment AB
Ray AB
A
A
A
B
B
B
D. Which rays on the drawing intersect? Prove it.
S
A
M
B
K
D
E
C
F
N
E. Yesterday Masha baked 32 pies and today she baked 4 pies more than yesterday.
Which questions can you ask about this given in order to make a problem:
How many pies did Masha bake yesterday?
How many pies did Masha bake today?
What stuffing did the pies have?
How many pies did she make in two days?
F. Match the questions above with the appropriate drawings:
G. Which operation do you have to put instead of the question mark? What is the reverse
operation?
?
a).
DOG
?
?
HOG
b).
1 m 5 cm
105 cm
?
H. Calculate the sum. What is the best way to calculate?
13 + 16 + 19 + 22 + 25 + 28 + 31 + 34 + 37 =
I. Identify the pattern and insert the missing numbers:
3
6
15
24
J*. Someday in the late fall it is raining heavily at 10 PM. Is it possible to have a sunny
weather 48 hours later?
Exercise 2:
Easy
Difficult
Interesting
Boring
A.
The drawings illustrate what Nick was doing in the morning. The drawings are all mixed
up but their order is easy to reconstruct with the help of the Nick's program of actions
in which the sequence of operations he has performed is indicated by means or arrows.
Wash and brush teeth
Dress up
Comb hair
Do the morning
exercise
Eat breakfast
Do the bed
Go to school
Wake up
The sequence of operations can be written in different ways: for example from the top
down.
The sequence of operations is also called an algorithm.
In the Nick's sequence of operations is it possible to swap doing the bed and doing the
morning exercise?
Is it possible to swap dressing up and going to school?
B. Consider the algorithms of development of a from and of a butterfly. On which stages
changes occur?
An egg
A larva
A tadpole
A caterpillar
A little frog
A cocoon
A mature frog
A butterfly
C. Make all possible equities from numbers and letters using the drawing:
T+C=S
5+4=⬜
⬜+⬜=⬜
⬜+⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
How else can you sort the shapes? Make Other possible equities from numbers and
letters.
⬜+⬜=⬜
⬜+⬜=⬜
⬜+⬜=⬜
⬜+⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
⬜–⬜=⬜
D. In a school there are 32 students in the team 2A, 28 students in the team 2B, and 30
students in the team 2C. There are totally 52 girls in all three teams. How many boys are
in the all three teams?
B
G
E. Walter has printed 18 large and 26 small photographs. Out of them he has given 5 to
his sister. He has given his grandma 3 more photographs than to his sister. After that
Walter put 8 photographs into his album and the rest has given to his mom. How many
photographs did he give to his mom?
S
Exercise 3:
G
A
Easy
Difficult
M
Interesting
Boring
A. This is a robot. His name is Bob.
Bob can memorize and follow
commands given by people.
Help Bob to plant a tree. Number the
drawings appropriately and write down
the algorithm to “plant a tree”.
Plant a tree
Begin
Bring a shovel, a water can , and a tree
Fill the hole with soil
End
an , an d
c
r
e
t
a
w
o vel, a
h
s
a
g
B rin
a tree
Pu t th e tree in to
th e h o le
Exercise 4:
Easy
Difficult
Interesting
Boring
This is Yant the alien. He has just
arrived on the Earth and does not yet
understand people well. When Yant is
unwell his skin turns green and his
ears drop down.
Why did Yant become sick? Find the mistakes in his actions and write him an algorithm
how to eat a banana.
Eat a banana
Begin
Wash your hands
Take a banana
Garbage
Exercise 5:
Easy
Difficult
Interesting
Boring
A. Four kids were playing snowballs. Andrew (A) threw his snow ball further than Nick
(N) and Victor (V), but closer than Serge (S).
Mark the correct drawing with a (+) and an incorrect drawing with a (-).
N
A
V
S
V
N
A
S
What is another possibility that would be in agreement with the given?
Mark the correct drawing if the spruce is higher than the birch tree but lower than the
oak.
Game Spruce Trees.
Game N1
Game N3
Game N2
Game N4
If you win draw a happy face. If you lose draw a sad face.
Two players take turns. Each player can draw any number of spruce trees in any one
row. When there are no more slots for the new trees the game is over. Whoever draws
the last tree is the winner.