HTML and CSS lesson 17: Pages everyone can use: accessibility

US version. US grades and US spelling. · UK version of this lesson

Accessible pages work for everyone: alt text, labels, headings in order, a page language and text with enough contrast (at least 4.5 to 1). A complete 40-minute HTML and CSS lesson for beginners (Grades 6–7), from Unit 6: Good pages for everyone. You build real web pages right here in your browser – nothing to install.

Time: 40 minutes + 20 min homework
Grade: Grades 6–7 (ages 11–12)
You need: A computer or tablet, paper and a pencil
Graded: Instantly, with explanations

For parents: how to use this lesson

You don't need to know HTML yourself. The lesson explains each step on screen, the way Mr Babbage, our Head of Computing, likes it: a worked example first, then a go for your child. When your child builds a page, the browser draws it straight away and Classfern grades it with a checklist.

Read what your child will learn together.
Press Start the lesson below. Sit with your child for the teaching and the worked example (about 15 minutes): ask them to point at each tag and say what it does.
Let them do the practice on their own. If a page doesn't look right, the checklist says what is missing – let them find the mistake before you help.
Finish with the exit questions and the talk question: “Try using a page with only the keyboard (Tab and Enter). What was hard?”
Later that day or the next day: the homework (20 minutes), then a practice test.

Watch out for

Accessibility is only for a few people. It helps everyone: phones in sunlight, tired eyes, slow connections.
Light gray on white is fine. It is often below 4.5 to 1.

Miss Lovelace's tip for home: ask your child to change one thing on their page – a word, a color, a size – and predict what will happen before they look. Predicting first is how programmers learn fastest.

What your child will learn

Learning goal: find and fix accessibility problems.

Success looks like

I can find and fix accessibility problems.
I can check text contrast.
I can explain who accessibility helps.

Key words

accessibility · screen reader · alt text · label · contrast ratio · heading order

What to have ready

A device with a web browser (pages are built and checked right in the browser – nothing to install)
Paper for planning and sketching
A keyboard helps for typing code (a tablet works too)

The big ideas (for the adult)

Many people use the web differently: with a screen reader that reads the page aloud, with the keyboard instead of a mouse, zoomed in, or with color blindness. An accessible page works for all of them – and is usually better for everyone else too.

The checklist from this course: every picture has alt text; every box has a label; headings go in order with one <h1>; the page says its language; links say where they go. These are things a computer can check.

Contrast is how different the text and background are in brightness. Normal text needs a ratio of at least 4.5 to 1 (black on white is 21 to 1). Pale gray text on white looks stylish but many people can't read it. Never use color alone to show meaning – add words too.

Worked example: a checklist page

CSS:

body { color: #222222; background-color: white; }

HTML:

<h1>Join the club</h1>
<img src="/assets/coding/html/img/bike.svg" alt="a red bicycle leaning on a wall" width="160">
<form>
<label for="nick">Nickname</label>
<input type="text" id="nick">
</form>

The lesson, step by step

40 minutes in 5 parts
Part	Time	How it is checked
Starter	5 min	Graded by Classfern
Learn	8 min	Read, watch and talk
See it	7 min	Graded by Classfern
Practice	15 min	Graded by Classfern
Check and reflect	5 min	Graded by Classfern + self-check

The lesson

It runs here on the page. No sign-up and no names – nothing you type is sent anywhere. Each visit picks a new mix of questions.

Homework

20 minutes: predict what the browser will do, build or fix a short page, and check the key ideas – then a short reflection. New questions every time, all graded instantly.

Practice tests

All computer science practice tests · All 20 HTML and CSS lessons

Curriculum

CSTA K–12 Computer Science Standards (2017), grades 6–8: 2-IC-21 – Discuss bias and accessibility in the design of existing technologies; 2-AP-17 – Systematically test and refine programs using a range of test cases.

The standard codes are CSTA's; the descriptions are our own words.

Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board. HTML and CSS are open web standards; Classfern is not affiliated with the organisations that publish them.