Build: A Calculator Program
Intro to Python Programming Grades 9–12 2-day lesson 23 deliverables Guide students as they plan and build a Python calculator for a trip or pizza party. Students decide what the user will enter, choose input types and write the math in plain words before coding. They check a partner's numbers by hand, compare those answers with the program's output and fix any differences.
● Instant download · Lifetime access · Editable & print-ready
Print + digitalPDF, PowerPoint, Word & Google
Answer keysA key for every page
Built-in assessmentExit tickets + project rubric
45-minute daysEvery day planned and timed
Short coding levels practice this lesson in CodeGrove, our code lab that runs in the browser. Students write the program, run it and check it, with no account and nothing to install. Use them with the lesson or as practice later.
See the levelsWhat does this lesson cover?
A calculator can print a result that looks reasonable even when its math is wrong. This build has students plan the calculation and check expected answers by hand before trusting the program.
The lab on Day 1 has an online version that uses CodeGrove, our in-browser code lab, in the Trip Planner or Pizza Party level. It practices building a calculator that asks for three numbers, does the math and prints a summary with two decimals for money. Students pick one of two builds, Trip Planner or Pizza Party. They plan their program, build it on the code sheet or in CodeGrove and test it with a partner. On the last day of the build, paper students hand in the code sheet, and online students send the turn-in Form with their CodeGrove link. Every online version comes with a paper version, so no internet is needed. CodeGrove is free, with no accounts or sign-ins.
Build Your Calculator
Students pick Trip Planner or Pizza Party, fill in an IPO chart on paper and start building on paper or in CodeGrove.
Everything that's included
00 Start Here
- READ FIRST: every file in the lesson and when you use it
- Teacher Guide and Pacing: the plan for each day, what to print and how to grade
- Skills map: which standards each day teaches
01 Present
- One editable PowerPoint deck for both days, 14 slides, with speaker notes
- Slide script: the speaker notes, printed
- Bell ringers: a short warm-up for each day
02 Student Handouts
- Guided notes: one packet for both days, in PDF and editable Word. Students fill in the blanks during the slides, with the word bank on the page
- Vocab slip: the lesson's words and what they mean, on one page
03 Labs
- Build Your Calculator: students pick Trip Planner or Pizza Party, fill in an IPO chart on paper and start building on paper or in CodeGrove
04 Activities
- Plan Your Calculator: students pick Trip Planner or Pizza Party, fill in an IPO chart and tell in plain words how their program works out each answer
05 Assessment
- Exit tickets: quick questions that show who needs more help
- Project rubric: what the whole project is graded on, row by row
06 Answer Keys
- 3 answer key files: a key for each day (its bell ringer, notes and exit ticket) and the activity and lab keys
Digital: Google Forms™ + Google Slides™
- 3 Google Forms™ of the exit tickets and the turn-in Form, ready to copy into your Drive
- The multiple choice grades itself, and you grade the written answers
- A Google Slides™ copy of the deck, with the same slides and speaker notes, for Google Classroom™
- Give a Form that asks students to read code only on school-managed Chromebooks in locked mode, and use the paper version on other devices
Online: CodeGrove
- CodeGrove, Trip Planner or Pizza Party level: the online version of the lab on Day 1
- Every online version has a paper version, so no internet is needed
- Free to use, with no accounts or sign-ins
Why teachers love this lesson
The plan connects inputs to resultsStudents use an input, process and output chart to connect typed numbers with the math and final message.
Hand math checks the program's workA partner supplies test numbers, and students compare their own calculation with what the program prints.
Print and digitalEvery page is a print-ready PDF, and the Google Forms™ and Google Slides™ let you teach the same lesson in Google Classroom™.
Real online activitiesStudents can use CodeGrove, our in-browser code lab, on a computer or tablet, and every online version has a paper version that works with no internet.
A key for every pageEvery day has its own answer key, and every written question has a sample answer and what to look for.
Every day fits a 45-minute classEach day's plan is timed activity by activity against real reading and writing speeds.
What Teachers Say
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How do I get the files after I buy?
Instant download right after checkout: PowerPoint and Word files you can edit, print-ready PDFs, and links that copy the Google Forms™ and Google Slides™ into your Drive.
Can I buy the whole unit or course instead?
Yes. This lesson is part of the Unit 2 bundle and the complete Intro to Python Programming course. Both cost less than buying the lessons one at a time.
Is this AP Computer Science?
No. It is a full-year, non-AP intro to Python course for grades 9 to 12. For AP, see our AP Computer Science A and AP CSP courses.
What should students know before this lesson?
Students can write comments, name variables in snake_case and print text and variables. They know that a TypeError or a ValueError names the line where Python stopped, and they can test a program with a partner's answers.
What formats are the files in?
Every page is a print-ready PDF. The slides are an editable PowerPoint and the guided notes an editable Word file. The exit tickets and the turn-in Form also come as Google Forms™, and the deck as Google Slides™.
Which standards does it cover?
Written for Florida's Foundations of Programming course (9007210). The skills map in the lesson shows which standards each day teaches.