STEAM Clown - Python - Variables, Data Types, & Expressions

Python - Chapter 1 - Introduction to Variables, Data Types, & Expressions

Python: Lessons, Lectures, & Labs - Robots & Rovers - 🤖🚙

Unit: Programming - Python & IOT
- Module: Python & IOT Introduction
This is a LEARNING & DOING : Lesson / Lab

Last Revised: Dec 22, 2025 - Authored: Dec. 28, 2020
Original Author: Jim Burnham - TopClown@STEAMClown.org
Content License: Distributed as Open Source. See Rights & Usage

Web Site: WWW.STEAMCLOWN.ORG | Contact: TopClown@STEAMClown.org | LinkedIn: Jim Burnham | You Tube: jimTheSTEAMClown | TikTok: STEAM Clown

Every rover, no matter how advanced, makes decisions based on data. Distance sensors measure how far away an obstacle is. Encoders report how fast the wheels are turning. Batteries provide voltage readings that determine how long the rover can operate. To control a rover using Python, we must be able to store this variable data collected from the sensors, work with it, and use expressions to compute results from it.

This chapter introduces the three fundamental building blocks that make all Python programs possible:

Variables — how Python stores and names values for later use
Data Types — how Python understands and categorizes information
Expressions — how Python performs calculations and evaluations

These concepts form the foundation of every robotics program. Whether you are calculating how far a rover can move forward, deciding when to stop to avoid an obstacle, or simply collecting and reporting a sensor reading to an output device, like an LCD screen, console monitor, or some other display device, you are using expressions, data types, and variables.

By the end of this chapter, you will be able to write simple but meaningful Python programs that model real rover behavior, even before you begin controlling physical hardware.

Chapter Roadmap: In this chapter, you will learn how to:

Create and name variables correctly
Identify and use common Python data types
Write and evaluate Python expressions
Combine variables and expressions to model rover behavior
Write Python code relevant to rover sensors, movement values, and robot state

These foundational skills will prepare you for upcoming chapters, where you will control program flow, respond to sensor input, and begin writing complete rover control programs.

8.1.C.N - Chapter N - Python - Topic - Sub Topic - 📰️ Slides

8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📰 Slide Presentation
- 8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📖 Lesson Tutorial
Mechatronics - <topic> - 📽️ Video / 🎧 Video/Podcast (TBD)
- Mechatronics - <topic> - LAB #1 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)
- Mechatronics - <topic> - LAB #2 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)

Why Python for Robotics?

Python is a powerful language that is readable, expressive, and widely used in robotics for sensor interaction, motor control, and decision logic:

Read sensor values (e.g., distance, light, temperature)
Store those values in variables
Compute decisions (e.g., “stop”, “turn”, “slow down”)
Send commands to actuators (e.g., wheels, servos)

Before controlling movement, you must understand how Python stores, evaluates, and manipulates data. These concepts: variables, data types & expressions, are the foundations of all Python programs.

Data Types First… Then We Will Talk About Variables

A Value is one of the basic pieces of data that a Python program can work with, such as a number or string. Every value in Python belongs to a Data Type — a category that tells Python what kind of value it is and how it behaves.
Python, like any other structured language has values in form of Variables, defined as Data Types and they are used to resolve Expressions.
Data Types represents the kind of value that tells what operations can be performed on a particular data.
Since everything is an object in Python programming, Data Types are actually classes and variables are instances (objects) of these classes.

Common Data Types

Integer (int)
- Whole numbers without decimals.
- Example: 42, -7
Floating-point number (float)
- Numbers with a decimal point.
- Example: 3.14, 0.0
String (str)
- Text enclosed in quotes.
- Example: "Forward", 'STOP'

Built-In Data Types

Data types are the classification or categorization of data items. Everything in python is an "object", and because of this, they need to be defined by a data type.
Numbers
- Integers
- Long Integers
- Floats
- Complex Numbers
Boolean Logic (True/False)
- bool

(More On These Later)

Lists
Tuples
Sets
Dictionaries
Strings
File Objects

Integers: int vs long?

In Python 3 (modern Python)

There is NO separate long type. (Python 3 merged them)
int handles all whole numbers
int = unlimited precision integer
Small or extremely large — Python manages it automatically

In Python, an int represents any whole number, and Python automatically handles very large values, so there is no separate long type.

x = 10

y = 999999999999999999999

Both are:

type(x) == type(y) # True

float Data Type

A float is a data type used to store numbers with decimal points. Floats are commonly used in robotics to represent:

Sensor distances
Voltages
Speeds
Time measurements

Floats allow more precise measurements than integers, but they can include small rounding errors, so they should be used carefully in comparisons. Use float whenever measurements are not whole numbers.

float in Robotics

Floats allow more precise measurements than integers
But they can include more significant digits and can include small rounding errors
They should be used carefully in comparisons. <-- More on this "rounding" in a later LAB
Use float whenever measurements are not whole numbers.

Floats as Scientific or Engineering Notation:

Floats may also be in scientific notation, with E or e indicating the power of 10. When a number is really really big or very very small, it is more readable to represent it as an exponent.
2.5e2 = 2.5 x 102 = 250
Big Numbers:
- 6.02214076e23 is Avogadro’s number, and it is very very big. You would have to agree that 6.0221407623 or 6.02214076e23 is more readable than 6.0221407600000000000000000000000
- 4.7e6 rather than 47000000, which might be a resistor value of 4.7MΩ
- 10e3 rather than 10000, which might be a resistor value of 10KΩ
- 7e9 = Population of the world is around 7 billion written out as 7000000000
- 1.08e9 = Approximate speed of light is 1080 million km per hour or 1080000000 km per hour
- 3.99e13 = Distance from the sun to the nearest star (Proxima Centauri) is 39900000000000 km
Small Numbers:
- These exponents can also be negative 2.2e-9 = 2.2 x 10-9 = .0000000022 or 2.2 pF
- You might also see some small number represented in scientific or engineering notation like: capacitor
  - 2.2e-9 rather than .0000000022, which might be a capacitor value of 2.2 x 10-9 = 2.2 pF
  - 2.4e-3 = Diameter of a grain of sand is 24 ten-thousandths inch or .0024 inch
  - 7.53e-10 = Mass of a dust particle is 0.000000000753 kg
  - 9.1093822e-31 = Mass of an electron is 0.00000000000000000000000000000091093822 kg
  - 4.0e-7 = Length of the shortest wavelength of visible light (violet) is 0.0000004 meters

Why Python for Robotics?

8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📰 Slide Presentation
- 8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📖 Lesson Tutorial
Mechatronics - <topic> - 📽️ Video / 🎧 Video/Podcast (TBD)
- Mechatronics - <topic> - LAB #1 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)
- Mechatronics - <topic> - LAB #2 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)

Why Python for Robotics?

8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📰 Slide Presentation
- 8.3.C.N - Chapter N - Python - Topic - Sub Topic - 📖 Lesson Tutorial
Mechatronics - <topic> - 📽️ Video / 🎧 Video/Podcast (TBD)
- Mechatronics - <topic> - LAB #1 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)
- Mechatronics - <topic> - LAB #2 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)

ChatGPT or Claude?

As a Teacher, I have reservations about students immediately asking ChatGPT as the first thought when trying to code something. I can see how these code LLM's are great for experienced Python developers, but Students without much experience will not understand code, or even know what they should expect... and that is the Key to being successful "Learning" while also getting help from LLM's.
- While using ChatGPT, I constantly see flagrant errors. Errors that many time cause me to waste time, or go down a "rabbit hole" just to understand what happened and if what the LLM said is valid. An inexperienced code would miss these errors, waste a huge amount of time, or worse, deploy code whit ah really bad bug or implementation.
- I have seen ChatGPT import old, obsolete or unsupported Libraries
- I have seen code where If statements are clearly inverted, and the logic flow is clearly wrong.

Prompt to help drive ChatGPT and Claude and other LLM's to work harder at providing well thought out code, which it has verified and followed rules.

Prompt Template for Generating Python Code Examples (Robotics / Embedded / Educational Focus)

Prompt:
"

Generate a Python code example for [specific robotics/embedded/educational task].

Follow these strict rules to ensure high-quality, maintainable, and educational code:

1) Library Selection:

Use only the latest, actively maintained Python libraries.
Do not use and avoid deprecated, obsolete, or unmaintained libraries.
Typically Lab examples should use Python code that is targeted to run on a Raspberry Pi
Justify every third-party library used: Why it is needed. What specific features are being used. Why the standard library alone is insufficient
Justify every library selection in comments or documentation. Explain why it is chosen for robotics or embedded applications.

2) Imports:

Every import must have a purpose; document what features are used and where it is used in the code.
Do not include unused, "future-Use", or convenience or unnecessary imports.
Never introduce a dependency unless strictly required and fully explained.
If a dependency is optional, provide a version without it.

3) Variables and Functions:

Every variable and function must have a clear role.
Use meaningful names reflecting robotics or embedded context (e.g., motor_speed, distance_sensor).
Include comments explaining why variables and functions exist.

4) Code Structure & Quality:

Follow PEP8 for readability.
Include docstrings for all functions/classes.
Write modular code suitable for educational purposes or embedded deployment. Examples should be Robotics or Autonomous Rover focused
The code must execute without modification in a standard Python environment.
State the required Python version (e.g., Python 3.11+).
Do not assume external files, hardware, or environment variables unless explicitly stated.
If hardware or simulated data is involved, clearly mock or emulate it.
Handle Common Errors Gracefully, Validate inputs where appropriate.
Avoid silent failures.
Clearly explain what errors may occur and why.

5) Requested Code Topics & Accompanying Lab Examples:

Target and tailor any code examples to Robotics and Autonomous Rover.
Examples should be targeted at Students learning Python, and have extensive documentation and tips and hints in the form of code comments.
No “Magic” Code. Avoid unexplained syntax, shortcuts, or idioms. If a construct might confuse students or beginners, explain it inline or in comments.
Explain why variables, functions, and data structures are named as they are.
Explain why the chosen approach is appropriate for the problem.
Comments should be intentional & explain why, not restate what the code already says.
Avoid redundant comments.
Code should be readable by someone learning Python.
Avoid premature abstraction.
Prefer step-by-step logic over compressed patterns.

6) Final-Pass Dependency & Logic Check:

Before presenting the final answer, perform a silent self-review against these rules and correct any violations.
Mentally execute the code to ensure:
- Every import is used
- Every variable is initialized and used appropriately
- All functions have a purpose
- No dead or redundant code exists
Document the final dependencies and their necessity.

7) Output & Visualization:

If visualizing data (sensors, lidar, plots), ensure the method works in a standard Python environment.
Prefer console-safe or simple plotting libraries suitable for educational and embedded demonstrations.

Provide the complete, ready-to-run Python example, fully documented, suitable for robotics/embedded/educational use.

Back is the awesome stuff about old stuff you already know...

Next is the awesome new lesson about stuff

Text Books, Reference, Tutorials & Other Online Resources: 🤖🚙

Text Book - Automate the Boring Stuff with Python, 2nd Edition: Practical Programming for Total Beginners

- This is a text book you will be using in class. Many of the lectures and Lessons will contain material from this book. You will be assigned reading and coding assignments pulled from this resource.
- On its own, this book won’t turn you into a professional software developer any more than a few guitar lessons will turn you into a rock star. But if you’re an office worker, administrator, academic, or anyone else who uses a computer for work or fun, you will learn the basics of programming so that you can automate simple tasks

Text Book - Think Python: How to Think Like a Computer Scientist (HTML) 3rd Edition

- This is an open sources Python Text book by Allen B. Downey, and you will be using it in class. Some of the lectures and Lessons will contain material from this book. You will be assigned reading and coding assignments pulled from this resource.
- The Author, Allen, had some specific goals when he wrote this book:
  - Keep it short. It is better for students to read 10 pages than not read 50 pages.
  - Be careful with vocabulary. I tried to minimize jargon and define each term at first use.
  - Build gradually. To avoid trap doors, I took the most difficult topics and split them into a series of small steps.
  - Focus on programming, not the programming language. I included the minimum useful subset of Python and left out the rest.
- PDF Version - Think Python: How to Think Like a Computer Scientist (PDF)
- HTML Version - Think Python: How to Think Like a Computer Scientist (HTML)

Reference Python Class - Python 4 Everyone

- This is an open sources Python College class taught by Dr Severance from the University of Michigan, and you will be using it in class. Some of the lectures and Lessons will contain material from this class. You will be assigned reading and coding assignments pulled from this resource.
- Python 4 Every one - Open Source University level Python class - Dr Charles Severance
  - Introduction by Dr Severance - 📽️ 🎧
  - Class Lessons & Videos - https://www.py4e.com/lessons - 📽️ 🎧 📰 📖 📝🛠️
  - Text Book - Python 4 Everybody (HTML) - 📝🛠️

More Python Reference Resources

Online Python Interpreters

- Browser-based Python Shell - https://www.python.org/shell/ - one command at a time
- Browser-based Python interpreter - replit.com - 🛠️ LAB Activity - Signup for free account (They have monetized this to be un-useful)
- Browser-based Python interpreter - trinket.io - 🛠️ LAB Activity - Signup for free account (Can't save projects)
- Python Tutor - Interactive Code Visualization site - See code execute, see memory allocations, etc
- Python Interpreter - Online GDB

Python Tutorial or Online Lesson Sites

- W3School Python Tutorials - Comprehensive Python Tutorial and Reference Examples with options to try out code
- Python Tutorial & Reference Guide - From Tutorials Point - Good Easy Learning - Reference & Examples
  - Python 2.7 On-Line Python Interpreter - Tutorials Point
- Python Reference from Valley Of Code - Python Online Reference, that is really good.
- CodeCademy - Python 3 - You can sign up. They want you to get a 7-day trial, but then they revert to a free option. Don't enter any Credit Card info, just register for the free options.
- Python Code In An Hour - This is an Hour-long Webinar (if the link is broken check here on YouTube for a crappy recording)

Python Code Examples and Labs

- (NEW) - exercism.org - Colding exercises. Solve coding exercises and get mentored to gain true fluency in your chosen programming languages. Exercism is open-source and not-for-profit. Not just Python, but lots of languages.
- Ziro Studio - Tutorial and coding in a fun 3D world. It has examples of some complex code, which you can modify and "see" what happens.
- CodingBat Python Exercises - Challenges you can practice coding. Check your code and even check for an implementation.

8.1.1.1 - Chapter 1 - Introduction to Variables, Data Types, & Expressions

8.1.0.1.1 - Chapter 1 - Introduction to Expressions, Data Types, and Variables - 📰 Slide Presentation
- 8.1.0.1.1 - Chapter 1 - Introduction to Expressions, Data Types, and Variables - 📖 Lesson Tutorial
Mechatronics - <topic> - 📽️ Video / 🎧 Video/Podcast (TBD)
- Mechatronics - <topic> - LAB #1 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)
- Mechatronics - <topic> - LAB #2 - 🛠️ LAB Activity (Coming Soon... Really, I'm working on it...)

Reference, Attribution & Resources:

License - "Be A Hero"... Distribute Your Content As Open Source... That Is What I'm Doing...

The content on this site may have been pulled from other open source sites, but typically the interpretation and presentation is primarily the Intellectual Property of Jim Burnham, - TopClown@STEAMClown.org at www.steamclown.org and the Student curriculum can be found under the specific Mechatronics Engineering Units section of this web site.
If you do use my material, and make changes, I would appreciate getting a copy... because if you are making changes, it means that you think there is a better way to teach this… and I would really appreciate understanding that. Please send me feedback on my Questions or Feedback form. Please don’t hesitate to ask questions or comment.
You also should keep and include my STEAM Clown Logo and Copyright in any derivative works you create. I would appreciate if you would include one of these images found on my Steam Clown License page and link it to www.steamclown.org

Teachers - Unit, Module and Lesson Plans

If you are a teacher and want to connect and teach this Lesson or Module, discuss how I teach it, give me feedback, please contact me at TopClown@STEAMClown.org

To access this Lesson Plan and the Teacher collaboration area, you will have needed to connect with me so I can Share the content with you. Please go to the Teachers & Partner Page, check out my Licensing and fill out my Collaboration and Curriculum Request Form. I'll review and then grant you access to the requested areas and lesson plans if they exist.

If you have questions or feedback on how I can make a presentation, lesson, lab better please give use my Feedback Form.

Standards Alignments & Objectives:

I’ll work on getting these in, but it’s the last thing I want to work on :-) When I have them updated, I’ll move to the top of the Lesson Plan.

NGSS: <list standard numbers>
California CTE Standards: <list standard numbers>
Related Instructional Objectives (SWBAT): <list standard numbers>
CCSS: nnn, RSIT: nnn, RLST: nnn, WS: nnn, WHSST: nnn, A-CED: nnn, ETS: nnn <list standard numbers>
Main Standard:
Priority standards:
National Standards:

Resource Attribution:
Sites Referenced or Summarized:

Reference Text Book - Links
Reference Sites -

Images:

https://imgbin.com/png/ZJtzkYZZ/under-construction-png

Resource Key:

<Unit> - <Module Name> - Lessons - Daily/Weekly Lesson Plan

Key: 📰 Slides / Audio 🎧 / 📽️▶️ Video/YouTube / 🎧▶️📽️ Audio/Video / ✨ Resources / 🖼️ Tutorial / 📖 Reading Activity / 📝 Writing Activity / 📖 📝 Reading/Writing / 📟 Coding / 🛠️ LAB Activity / 🚀 Quiz / 🔎 Review / ✔️ Mastery Check / ✍️ Sign Up /🍕 Extra Credit / 🕸️ Web Links / 👩🏽‍🎓🧑🏽‍🎓🧑🏿‍🎓👩‍🏫 Class / 🏵️📜📃 Certificate / 🗂️ 📈 Collecting Survey Data

/🧟 Review / 🦾 Practice / 🆙Level Up /

🎚️🦑📤🎯 🚧

- 🦑 Special Project -

Assignment Type: ⚓ Establishing (Minimum Standard) / ⛏️ Developing (Digging Deeper) / 💎 Aspiring (Putting It Together)

This is an ⚓ Establishing Assignment (Minimum Standard) - "Everyone Do" Assignment

This is an ⛏️ Developing (Digging Deeper) - "Everyone Should Do, To Stretch" Assignment

This is an 💎 Aspiring (Putting It Together) - "When you have done the ⚓ Establishing and⛏️ Developing" Assignment

🚀 Formative Quiz - 🔎 Review
🚀 Quiz -🔀 Mastery Path
🚀 Summative Quiz -✔️ Skills Mastery Check

Quiz - verify that they are all listed as a "Formative", "Mastery Path", or "Summative"

🚀 Formative Quiz - These are quizzes that the students can take a few times. I have them either set for unlimited times, or 3-5 times, where the final score is their average. The idea is that these Formative Quizzes are designed for students to learn and master a skill. while I want them to ger 100%, and when it's set to unlimited tries, the student should get 100% eventually. When the quiz is set to 3-5 tries with an average, then they should be prepared and should take the quiz seriously. I set the quiz to not show the right answer, but I do let them see their wrong answer. I also put the explanation of the right and wrong answer in the right and wrong answer prompt for each question. That way they can see why they got the answer wrong and learn from that experience.
- 8.1.0.3.2.4 - Python - Ch 3 - Functions - Quiz #2 -Built-In Functions - 🚀 Formative Quiz
🚀 Quiz -🔀 Mastery Path - These Mastery path quizzes are to be presented after the student has had a chance to do some labs and some Formative quizzes. The goal is to let students have 2 chances to take this quiz, and take the average of the 2 attempts. Based on the average, they will be presented with a Canvas Mastery Path, where they will have an option for take additional quiz and assignments to help with remediation. This will get them ready to take the Summative Quizzes.
- 8.1.0.3.3.1 - Python - Ch 3 - Functions - Mastery Quiz #1 - 🚀 Quiz -🔀 Mastery Path
🚀 Summative Quiz -✔️ Skills Mastery Check - These Mastery path quizzes are to be presented after the student has had a chance to do some labs and some Formative quizzes. The goal is to let students have 2 chances to take this quiz, and take the average of the 2 attempts. That will be their final module/subject topic grade.
- 8.1.0.3.3.1 - Python - Ch 3 - Functions - Skills Mastery Check Quiz #1 - 🚀 Summative Quiz -✔️ Skills Mastery Check

Random Stuff To Sort

Raspberry Pi Resources on Kerry Bruce's Google drive
Cheat sheet - https://programmingwithmosh.com/python/python-3-cheat-sheet/
good tutorial series - Introduction and Parts - Raspberry Pi and Python tutorials p.1 - maybe assign this as home work when we take our Raspberry Pi's home
Element 14 - Getting Started With The Raspberry Pi 3
How To Log Into Python Learning Sites
https://realpython.com/
TryPython - Fun Interactive Class (you have to pay now)
CodeCademy - Learn Python

More Random site use as reference while creating this site

https://www.cgl.ucsf.edu/Outreach/pc204/objectives.html
Random Resource Links - Stuff to review and sort...
UC Davis C-STEM - C++ & Python for Raspberry Pi
VnC Connect - Raspberry Pi
This is where my Raspberry Pi Resource will go... they will show up in about 2 weeks (Jan 7 2019)... in the mean time you can see my Python Resource page from last year 2017-2018 <-- this will go away as soon as I have made this organizational update

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Python - Chapter 1 - Introduction to Variables, Data Types, & Expressions

8.1.C.N - Chapter N - Python - Topic - Sub Topic - 📰️ Slides

Why Python for Robotics?

Data Types First… Then We Will Talk About Variables

Common Data Types

Built-In Data Types

Integers: int vs long?

float Data Type

float in Robotics

Floats as Scientific or Engineering Notation:

Why Python for Robotics?

Why Python for Robotics?

ChatGPT or Claude?

Prompt Template for Generating Python Code Examples (Robotics / Embedded / Educational Focus)

Text Books, Reference, Tutorials & Other Online Resources: 🤖🚙

Text Book - Automate the Boring Stuff with Python, 2nd Edition: Practical Programming for Total Beginners

Text Book - Think Python: How to Think Like a Computer Scientist (HTML) 3rd Edition

Reference Python Class - Python 4 Everyone

More Python Reference Resources

Online Python Interpreters

Python Tutorial or Online Lesson Sites

Python Code Examples and Labs

8.1.1.1 - Chapter 1 - Introduction to Variables, Data Types, & Expressions

Reference, Attribution & Resources:

License - "Be A Hero"... Distribute Your Content As Open Source... That Is What I'm Doing...

Teachers - Unit, Module and Lesson Plans

Standards Alignments & Objectives:

Resource Attribution:Sites Referenced or Summarized:

Images:

Resource Key:

<Unit> - <Module Name> - Lessons - Daily/Weekly Lesson Plan

Random Stuff To Sort

Mechatronics Python Class Slides

Code Example Sites

Tutorials

Links To Web Based Python Compilers

Reference Sites

More Random site use as reference while creating this site

Resource Attribution:
Sites Referenced or Summarized: