Form not sending out select and checkbox inputs in Angular 2 - forms

Question

I'm working on a small Angular 2 To-do app. I didn't want to have any problems with browser compatibility with inputs types like date, datetime-local, etc., so I did make <select> inputs for user to type in the date and time. Everything works fine, inputs are dynamic, so the user cannot choose the day that does not exist (like e.g. 02/29/2017), etc.
The problem is, I want to send form's data to the service and then to the Back-End of my app, but when I submit the form, values from <select> inputs are not included in the sent object, as well as my checkbox input. I'm not often using these types of inputs, so I'm sorry if this is a noobish question, but I cannot figure out what I'm doing wrong.
Here is the code:
<form #f="ngForm" (ngSubmit)="add(f.value)">
<div *ngIf="error">
<p>{{ error }}</p>
</div>
<div class="login-input-container">
<input type="text" placeholder="title" name="title" ngModel autocomplete="off" required minlength="1" maxlength="100">
</div>
<div class="login-input-container">
<div class="datetime-container">
<div>
<select #year name="year" (change)="showMonths(); selectedYear = year.value; yearDays(year.value);" required>
<option class="invisible" value="" disabled selected>year</option>
<option *ngFor="let year of years" [value]="year" placeholder="year">{{ year }}</option>
</select>
<select #month *ngIf="showedMonths" name="month" (change)="showDays(month.value, year.value); selectedMonth = month.value;" required>
<option class="invisible" value="" disabled selected>M</option>
<option *ngFor="let month of months" [value]="month">{{ month }}</option>
</select>
<select *ngIf="showedDays" name="day" (change)="showTime()" required>
<option class="invisible" value="" disabled selected>d</option>
<option *ngFor="let day of days" [value]="day">{{ day }}</option>
</select>
</div>
<div *ngIf="showedTime">
<select name="hours" required>
<option class="invisible" value="" disabled selected>hh</option>
<option *ngFor="let hour of hours" [value]="hour">{{ hour }}</option>
</select>
:
<select name="minutes" required>
<option class="invisible" value="" disabled selected>mm</option>
<option *ngFor="let minute of minutes" [value]="minute">{{ minute }}</option>
</select>
</div>
</div>
</div>
<div class="login-input-container">
<textarea id="todo-description" type="text" placeholder="description (optional)" name="description" ngModel autocomplete="off" minlength="1" maxlength="500"></textarea>
</div>
<div class="login-input-container">
<span><p>should we notify you?</p><label for="notify-1"><input id="notify-1" type="checkbox" [checked]="todo.notify" value="1"><span></span></label></span>
</div>
<div class="login-input-container">
<input type="submit" value="Submit" (click)="error = ''">
</div>
</form>

Answer 1

If you use [value] or [ngValue] you need to use [(ngModel)] or ngModel (ngModelChange)="showMonths()..." instead of `(change)="..."