CSTA.2-AP-10✓ Massachusetts Dept of Elem & Sec Education AlignedAcademic Year 2026–27
Python for Beginners: Variables, Loops & Functions
Learn the fundamentals of computational thinking in Python: variables, conditional if-else statements, for loops, and modular reusable functions.
Why It Matters:Powers artificial intelligence, web backends, scientific computing, and autonomous robotics worldwide.
Curated Video Instruction
● Verified Active EmbedSTEP-BY-STEP PROOF
Worked Example
Write a Python function to calculate the sum of all even numbers from 1 to N:
1
Define the function and initialize an accumulator
def sum_evens(n):
total = 0
Create a reusable function and set total to 0.
2
Iterate through numbers from 1 to n
for i in range(1, n + 1):
The range(1, n + 1) function generates integers 1, 2, ..., n.
3
Test even condition using modulo operator
if i % 2 == 0:
total += i
i % 2 == 0 checks if i is divisible by 2 with remainder 0.
4
Return the final accumulated total
return total
Yields the result back to the caller.
✓Verification Check
Run sum_evens(6): Evens are 2, 4, 6.
Expected: 2 + 4 + 6 = 12.
•
sum_evens(6) outputs 12. Correct!
⚠️ Common Pitfalls & Misconceptions
Off-by-one errors with range()
✗ range(1, n) stops at n - 1✓ range(1, n + 1) includes n
Python range() is half-open: it includes the start value but stops BEFORE the stop value.
INTERACTIVE DRILLS
Guided Practice
Practice Question1 of 1
Step-by-step Feedback
What does 14 % 4 evaluate to in Python?
MASTERY BENCHMARK
Official Assessment Quiz
Formal Assessment
Python for Beginners: Variables, Loops & Functions
Passing Criteria:70% or higher
Question 1 of 1
Which keyword is used to define a function in Python?
Education to Career Navigation
Where This Lesson Leads
Full Stack Developers, AI Engineers, and Data Scientists write Python to process information and build intelligent applications.