In my flask app, when I use request.form.get to get the value selected option, I get always none. Why?(I have name attribute to select tag)

Question

I'm creating a Flask app, and in my tellmestory.html I have a form for users to select the age. In my app.py, I am trying to select the user's selected option but I always get None.

Here are some snippets of my code:

In my app.py I have this list and 2 routes:

AGE=[
    "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"
]
@app.route("/tellmestory")
def tellmestory():
    return render_template("tellmestory.html", authors=AUTHORS, age=AGE, themes=THEMES)

@app.route("/story", methods=["POST"])
def story():
    child_age = request.form.get("child_age")
    return render_template("story.html", child_age=child_age)

In tellmestory.html I have this form:

        <form action="/story" method="post">
            <div class="form-group justify-content-center">
                <label for="child_age">Select child's age:</label>
                <select id="child_age" class="form-select" name="child_age" aria-label="Select  child's age">
                    <option disabled selected>Select child's age</option>
                    {% for child_age in age%}
                        <option value="{{ child_age }}">{{ child_age }}</option>
                    {% endfor %}
                </select>
            </div>
        </form>

In story.html I'm using Jinja to plug in the input:

    <div class="container d-flex justify-content-center">
        {{child_age}}
    </div>

Is this code correct or am I missing something?(I'm a beginner)