Yes! Kids can learn PythonChapter 1

Copyright 2018-2020 © Kent Tong (i-Study)

1

Go to https://p4kweb.appspot.com

Click this button.

Step forward, execute and reset

1: Input this.

2: Execute. Then do it once more. 3: Reset the game &

then execute again.

Command, function and call a function

step is a command/function.

To execute a command, you put parentheses () after it.

To call a function is the same as to execute a command.

Exercise: walk to the treasure box

Sample solution● Click the Exec button five times.

Can input multiple commands

They will be executed one by one.

The whole thing is called a program.

Exercise: Walk to the treasure box in one execution

Sample solution

step()step()step()step()step()

What if you spell the command incorrectly?

stop()step()step()step()step()

You will get an error message.

Pick up the treasure box

pickup()

Exercise: Walk to the treasure box & pick it up

Sample solution

step()step()step()step()step()pickup()

What does jump do? Try it

jump()

Change to another background

Choose this background.

Exercise: Jump over the hole & pick up the box

Sample solution

step()step()jump()step()pickup()

What does walk(3) do? Try it

Argument

walk(3)

3 is called an argument here. It doesn't mean arguing with someone. It is the information you hand to the command.

Exercise: Call walk & then pick up the box

Sample solution

walk(2)jump()step()pickup()

Not every function accepts an argument

walk(2) step(2)jump(3)

Perform calculation

walk(1+2)walk(3-1)walk(2*3)

What does print do? Try it

print(123)print(2*6)print(2*(3+1))print(10/2)

It outputs the values

The output goes to here.

Calculate & print the result● A slice of cake costs 6 dollars. A bottle of soda costs 5 dollars. How much do

they cost in total?

Sample solution

print(6+5)

Use variables to show the meanings of numbers

print(6+5) cake=6soda=5print(cake+soda)What does 6 mean?

cake=6 creates a variable

cake=6soda=5print(cake+soda)

This line creates a variable named "cake" and its value is 6.

cake

6

A variable must have two things: a name & a value

cake=6soda=5print(cake+soda)

cake

6

(name)

(value)

Exercise: Draw a diagram to show the variable soda

cake=6soda=5print(cake+soda)

Sample solution

cake=6soda=5print(cake+soda)

soda

5

Looking up the value of a variable

cake=6soda=5print(cake+soda)

soda

5

cake

6

What if there is a typo in the variable name?

cake=6soda=5print(coke+soda)

soda

5

cake

6

Can't find a variable named "coke".

You will get the "not defined" error

When creating a variable, a value is calculated first

a=2+6print(a)

The value is calculated first (8 in this case).

Then, let the variable point to that value.

a

8

Draw a diagram to show the variable b

b=3*5print(b)

Sample solution

b

15

Can use a variable to store the result

cake=6soda=5print(cake+soda)

cake=6soda=5total=cake+sodaprint(total)

Exercise: How many variables are created below? Draw a diagram to show eachcake=6soda=5total=cake+sodaprint(total)

Sample solution: three

soda

5

cake

6

total

11

cake=6soda=5total=cake+sodaprint(total)

Calculate & print the result while using variables● A slice of cake costs 6 dollars. You pay 10 dollars. What is the change?

cake=6soda=5total=cake+sodaprint(total)

For reference

Sample solution

cake=6payment=10change=payment-cakeprint(change)

Draw a diagram to show the variables below

cake=6payment=10change=payment-cakeprint(change)

Sample solution

cake=6payment=10change=payment-cakeprint(change)

payment

10

cake

6

change

4

Calculate & print the result while using variables● A slice of cake costs 6 dollars. How much are 3 slices of cake?

Sample solution

cake=6slices=3total=cake*slicesprint(total)

Calculate & print the result while using variables● 3 bars of chocolate cost 12 dollars. How much is a bar of chocolate?

Sample solution

total=12bars=3chocolate=total/barsprint(chocolate)

Exercise: Jump onto the platform & get the box

Choose this background first.

Sample solution

walk(2)jump()walk(2)pickup()

Exercise: go upstairs & get the box

Choose this background first.

Sample solution

walk(4)jump()walk(4)jump()walk(4)pickup()

Exercise: Use a variable to represent 4walk(4)jump()walk(4)jump()walk(4)pickup()

_____=4walk(_____)jump()walk(_____)jump()walk(_____)pickup()

Sample solution

width=4walk(width)jump()walk(width)jump()walk(width)pickup()

the width of the staircase