SOURCE

<section>
    <div class="a-text">1</div>
    <div class="a-img1">2</div>
    <div class="a-text">3</div>
    <div class="a-img2">4</div>
    <div class="a-text">5</div>
    <div class="a-img3">6</div>
    <div class="a-text">7</div>
</section>

div {
    height: 100vh;
    background-color: rgba(0, 0, 0, .7);
    color: #fff;
    line-height: 100vh;
    text-align: center;
    font-size: 10vh;
}

.a-img1 {
    background-image: url(https://images.pexels.com/photos/1097491/pexels-photo-1097491.jpeg);
    background-attachment: fixed;
    background-size: cover;
    background-position: center center;
}

.a-img2 {
    background-image: url(https://images.pexels.com/photos/2437299/pexels-photo-2437299.jpeg);
    background-attachment: fixed;
    background-size: cover;
    background-position: center center;
}

.a-img3 {
    background-image: url(https://images.pexels.com/photos/1005417/pexels-photo-1005417.jpeg);
    background-attachment: fixed;
    background-size: cover;
    background-position: center center;
}