Components of a mobile application

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A button, a text box and a label on a screen are examples of which mobile app component?

A Interface controls on a screen

B External libraries

2. Which describes an object in a mobile app?

A It is a screen that only displays pictures

B It holds data and behaviour together, like a Player with a score and a jump action

3. A user taps the Save button and the app stores their note. Which component responds to the tap?

A An event handler

B A label control

4. Which statement about event handlers is correct?

A They run only once, when the app is first installed

B They run in response to a user action such as a tap or swipe

5. Your team adds a ready-made maps library so the app can show a map. What is a library?

A Ready-made code written by others that your app can reuse

B A folder where the app stores user photos

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1button.onClick(save_score)		ABrings in a library of ready-made code, such as map features, so the app does not need to build them
2import maps_library		Bscreen.add(Label('Score'), Button('Play'))
3An object holds data (attributes) and behaviour (methods) together		Cplayer = Player('Ava', 120) player.add_points(10)
4A screen is made from interface controls such as labels and buttons that the user sees and taps		DThe object's data is mixed up: a text value is added to a number, which causes an error. Score should hold a number, such as player.score = 10 + 5.
5button.onClick(save_score())		EThe handler is called straight away because of the brackets, so it runs when the screen loads, not when the user taps. Pass the function name without brackets.
6player.score = 'ten' + 5		FAn event handler: when the user taps the button, the save_score function runs

Definitions

app components

Fill in the Blanks

Complete each line of code by filling in the missing parts.

btn = ______(root, text="Go", command=start)

class Player: def ________(self, name): self.name = name

btn = Button(root, _______=on_tap)

______ requests data = requests.get(url)

root = Tk() label = Label(root, text="Score") root.________()

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A w = tk.Tk()

B lbl = tk.Label(text="Hi", w)

C lbl.pack()

D w.mainloop()

Question 2

A def go():

B print("Tapped")

C b = tk.Button(w, command=go())

D b.pack()

Question 3

A class Task:

B def __init__(self, name):

C name = name

D t = Task("Homework")

Question 4

A import Random

B dice = random.randint(1, 6)

C print(dice)

Question 5

A import tkinter as tk

B w = tk.Window()

C box = tk.Entry(w)

D box.pack()

Answer Key

Components of a mobile application

Section A: Quick Questions

A — Interface controls on a screen

B — It holds data and behaviour together, like a Player with a score and a jump action

A — An event handler

B — They run in response to a user action such as a tap or swipe

A — Ready-made code written by others that your app can reuse

Section B: Match the Pairs

button.onClick(save_score) → An event handler: when the user taps the button, the save_score function runs

import maps_library → Brings in a library of ready-made code, such as map features, so the app does not need to build them

An object holds data (attributes) and behaviour (methods) together → player = Player('Ava', 120) player.add_points(10)

A screen is made from interface controls such as labels and buttons that the user sees and taps → screen.add(Label('Score'), Button('Play'))

button.onClick(save_score()) → The handler is called straight away because of the brackets, so it runs when the screen loads, not when the user taps. Pass the function name without brackets.

player.score = 'ten' + 5 → The object's data is mixed up: a text value is added to a number, which causes an error. Score should hold a number, such as player.score = 10 + 5.

Section C: Definitions

app components — The parts that make up a mobile app: interface controls on screens, objects with data and behaviour, event handlers that respond to the user, and libraries of ready-made code.

Section D: Fill in the Blanks

btn = Button(root, text="Go", command=start)

class Player:
    def __init__(self, name):
        self.name = name

btn = Button(root, command=on_tap)

import requests
data = requests.get(url)

root = Tk()
label = Label(root, text="Score")
root.mainloop()

Section E: Spot the Error

B — The parent window w is a positional argument and must come before the keyword argument text=. The correct line is lbl = tk.Label(w, text="Hi"), which puts the Label control on the screen.

C — Writing go() runs the handler straight away and passes its result to the button. The button needs the handler itself, so use command=go with no brackets. Then go runs when the user taps.

C — This only changes a local variable, so the object never stores its data. It should be self.name = name, so the Task object keeps the name.

A — Python module names are case-sensitive. The library is called random in lowercase, so it must be imported as import random before its code can be used.

B — tkinter has no Window class. The main app window is created with tk.Tk(), so the line should be w = tk.Tk().