ขอคำแนะนำทำระบบข้อสอบ / แบบฝึกหัด / ควิซ(Quiz) หน่อยค่ะ

// ในส่วนนี้เพื่อนแนะนำว่าให้เก็บเป็น SESSION ไว้เรียกคำตอบที่ตอบจาก radio
// แต่พอเปลี่ยนหน้ามันก็บันทึกทับไปค่ะ
foreach ($_POST as $key => $value[]) { }
    $_SESSION["ans"] = $value;
for ($is = 0; $is < count($_SESSION["ans"]); $is++) {
    echo $_SESSION["ans"][$is];
}

$total_records_per_page = 4;
$offset = ($page_no - 1) * $total_records_per_page;
$previous_page = $page_no - 1;
$next_page = $page_no + 1;
$result_count = mysqli_query(
    $conn,
    "SELECT COUNT(*) As total_records FROM `exam_tch` WHERE course_id = '1' AND ID_exam_group = '13'"
);
$total_records = mysqli_fetch_array($result_count);
$total_records = $total_records['total_records'];
$total_no_of_pages = ceil($total_records / $total_records_per_page);
$second_last = $total_no_of_pages - 1;
$result = mysqli_query(
    $conn,
    "SELECT * FROM `exam_tch` WHERE course_id = '1' AND ID_exam_group = '13' 
    LIMIT $offset, $total_records_per_page"
);
?>
<form name="xcheck" method="post" action="testcrud.php">
    <?
    $i = 0;
    if ($page_no > 1) {
        $i = ($total_records_per_page * $page_no) - $total_records_per_page;
    }
    while ($row = mysqli_fetch_array($result)) {
        $i++;
        echo '<div class="tab">';
        echo $i . '). ' . $row["exam_ques"] . '<br><br>';
        ?>
        <div class="form-check">
            <input class="form-check-input" type="radio" id="choice1.<?php echo $row['ID_exam_tch'] ?>"
            name="choice.<?php echo $row['ID_exam_tch']; ?>" value="1">
            <label class="form-check-label" for="choice1.<?php echo $row['ID_exam_tch'] ?>">
                <?php echo $row['exam_correct'] ?>
            </label>
        </div>
        <div class="form-check">
            <input class="form-check-input" type="radio" id="choice2.<?php echo $row['ID_exam_tch'] ?>"
            name="choice.<?php echo $row['ID_exam_tch']; ?>" value="2">
            <label class="form-check-label" for="choice2.<?php echo $row['ID_exam_tch'] ?>">
                <?php echo $row['exam_w_1'] ?>
            </label>
        </div>
        <div class="form-check">
            <input class="form-check-input" type="radio" id="choice3.<?php echo $row['ID_exam_tch'] ?>"
            name="choice.<?php echo $row['ID_exam_tch']; ?>" value="3">
            <label class="form-check-label" for="choice3.<?php echo $row['ID_exam_tch'] ?>">
                <?php echo $row['exam_w_2'] ?>
            </label>
        </div>
        <div class="form-check">
            <input class="form-check-input" type="radio" id="choice4.<?php echo $row['ID_exam_tch'] ?>"
            name="choice.<?php echo $row['ID_exam_tch']; ?>" value="4">
            <label class="form-check-label" for="choice4.<?php echo $row['ID_exam_tch'] ?>">
                <?php echo $row['exam_w_3'] ?>
            </label>
        </div>
        <br>
        <hr>

    <?php
    }

    echo '</div>';
    mysqli_close($con);

    ?> <?
        if ($page_no >= $total_no_of_pages) { ?>
        <input type="submit" name="btnsubmit" class="button" value="ส่งคำตอบแล้วสิ้นสุดการทำแบบทดสอบ">
    <?php } else {
        if ($page_no < $total_no_of_pages) { ?>
            <input type="submit" class="button" value="ถัดไป" formaction="?page_no=<?php echo $next_page ?>">
        <?php }
    }
    ?>
</form>