First of all, I want to clarify that I'm just learning ASP MVC and Umbraco :). There may be very novice mistakes. I'm trying to make a system of interviews. Searching the Internet, I found an example I changed my taste. I created an empty project for testing, and this is all I have.

Umbraco admin

DocumentTypes 
    Answer  // -->  Without template (for the moment) - No have properties (for the moment)
    Poll    // -->  Without template (for the moment) - No have properties (for the moment) - Have many "Answer" child and "Active" bool property
    Polls   // -->  Without template (for the moment) - No have properties (for the moment) - Have many "Poll" child 

PartialView
    Polls

Umbraco content

In Visual Studio

Umbraco CMS (NuGet) 7.4.2

Controllers
    PollController

Models
    PollViewModel
    Answer

SurfaceController

namespace Polls.Controllers
{
    public class PollsController : SurfaceController
    {

        [HttpPost]
        public ActionResult Submit(PollViewModel model)
        {

            // Do something...

            return RedirectToCurrentUmbracoPage();
        }

        public ActionResult Index()
        {
            var testPage = Umbraco.Content(CurrentPage.Id);
            var questions = new List<PollViewModel>();

            foreach (var currentPoll in testPage.Where("Active"))
            {
                questions.Add(new PollViewModel { ID = currentPoll.ID, Title = currentPoll.Name.ToString(), Answers = AnswerList(currentPoll.ID) });
            }

            return PartialView("~/Views/Polls.cshtml", questions);
        }

        private List<Answer> AnswerList(int myQuestionID)
        {
            var questionPage = Umbraco.Content(myQuestionID);
            var answers = new List<Answer>();

            foreach (var currentAnswer in questionPage.Children)
            {
                answers.Add(new Answer { ID = currentAnswer.ID, Text = currentAnswer.Name.ToString() });
            }

            return answers;
        }

    }
}

Model

namespace Polls.Models
{
    public class Answer
    {
        public int ID { get; set; }
        public string Text { get; set; } // --> No use for now
    }
}

namespace Polls.Models
{
    public class PollViewModel
    {
        public int ID { get; set; }
        public string Title { get; set; } // --> No use for now
        public List<Answer> Answers { get; set; }

    }
}

PartialView "Polls"

@model IEnumerable<Polls.Models.PollViewModel>

<div>
    @using (Html.BeginUmbracoForm<Polls.Controllers.PollsController>("Submit"))
    {

        foreach (var item in Model)
        {
            <div>
                @Html.Hidden(item.ID.ToString())
                <p>
                    <strong>@item.Title</strong>
                </p>
                @{
            foreach (var answerItem in item.Answers)
            {
                <div>
                    @Html.RadioButton(item.Title, answerItem.ID, new { @id = answerItem.ID })
                    @Html.Label(answerItem.Text, new { @for = answerItem.ID })
                </div>
            }
                }
            </div>
        }

        <div>
            <button type="submit">Send...</button>
        </div>

    }
</div>

Error (When I try to compile the solution)

Second question

How do I filter children by custom bool property? "Poll" DocumentType have a "Active" bool property.

This is correct?

foreach (var currentPoll in testPage.Where("Active")) { ... }

THX!!!!