my-element.html

<template>
  <div class="field">Test: ${myattr}</div>
</template>

my-element.js

import {bindable} from 'aurelia-framework';

export class MyElement {
  @bindable myattr;
};

page.html

<template>
  <section>
    <require from="my-element"></require>
    <my-element myattr.bind="'Something!'"></my-element>
  </section>
</template>