HTML

In an empty span, add a child span with a class called point for each point of the star.

<span class='foobar'>
    <span class='point'></span>
    <span class='point'></span>
    ...
</span>

Sass Mixin

Include the mixin in the parent span, specifying the color, the length of one side of the container, number of points, and width of the points.

.foobar {
    @include star(
        color,
        container size in px,
        ;points,
        point width in px
    );
}

Done!

Mixin use for this example: star(#f88,240px,5,40px)