Data model

Set up the data model and collections.

Data model: add a new grade

In this lesson you will add a new grade to the grades list with append. append puts an item at the end of the list and grows it:

grades.append(95)
print(len(grades))  # 4

The starting code includes the previous lesson's solution — grades = [85, 90, 78] and print(grades) are ready. You will add the append call and new output.

This shows the list growing dynamically.

Exercise Add a new grade and print the count

Write grades.append(95). Then write print("eklendi:", len(grades)).

Show example solution

grades = [85, 90, 78]
print(grades)
grades.append(95)
print("eklendi:", len(grades))

Next step: business logic

The data model is ready — you can now dynamically add grades to the list. In the next lesson you will add a business logic layer: computing the average with sum and len.

This layer will turn raw data into a meaningful result. The average is a fundamental statistic that summarises the grades. The starting code carries the previous solution; you only add the calculation.

Test yourself

Match the data model

append

Adds to end
len(grades)

Item count
[85, 90, 78]

Three-grade list
95

New grade
What does grades.append(95) do?
- Puts 95 at the start
- Removes 95
- Adds 95 at the end
- Empties the list
Show answer

Adds 95 at the end — append always adds the item at the end of the list.
Complete the append call
```
grades.____(95)
```
Show answer
```
grades.append(95)
```

Next lesson: Business logic

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