Module 1: Validating Websites

Overview

Throughout this course, the importance of complying with web standards has been stressed. Complying with standards assures that web content can be reliably viewable across a wide variety of browser-enabled technologies, and assures that users with disabilities will be able to access the content. A variety of tools are available to test whether or not web pages are compliant with web standards. This module explores those tools.

Lesson 1: Validating Your HTML

• Estimated time required: 30 - 60 minutes
• Link to student Lesson 1 page

Tips for Delivering This Lesson

• When using an automated validation tool, it's common for one error to cause a domino effect in which subsequent errors are erroneously reported. Therefore it's important to fix errors in sequence, and re-check after fixing each error. Often by fixing one error, the number of reported errors will decrease significantly.
• The greatest challenge in using validators is understanding their output. Sometimes the reported error is incomprehensible to the student (and maybe even the instructor). Students should still try to find the error and seek help from others, but by the time your class gets to this module you might be pressed for time, in which case you might decide its acceptable to proceed without having solved all errors.
• When frustrated by difficult-to-understand validation errors, it might be tempting to fall back on the real world as an example. In reality, few pages pass validation. Curious students may have already discovered that major sites such as Facebook.com, Google.com, or Amazon.com have scores or hundreds of validation errors. We encourage you to resist this temptation. A goal of this curriculum is to help build a workforce of the future in which designers, developers, and engineers are sensitive to the importance of standardization and accessibility. Just because a site is popular doesn't mean it works on all devices or is accessible to all users. In fact, this is sadly is often not the case. Fortunately, standards conformance and accessibility are slowly becoming a higher priority in the commercial sector, driven in part by the proliferation of mobile technologies, and by laws that require accessibility. Meanwhile, there are plenty of bad examples out there on the Web, and students should be encouraged to exceed the quality of these examples. By creating a site that is 100% valid and standards-conformant, students can boast that they're developing code that is better than some of the most famous sites on the Web.

Lesson 2: Validating Your CSS

• Estimated time required: 30 - 60 minutes
• Link to student Lesson 2 page

Tips for Delivering This Lesson

• See Lesson 1 tips. They're applicable to this lesson as well.

Lesson 3: Validating Your Accessibility

• Estimated time required: 30 - 60 minutes
• Link to student Lesson 3 page

Tips for Delivering This Lesson

• This lesson is designed to be taught to the entire class, but you can have students do the lesson individually.
• One important difference between HTML/CSS validation and accessibility evaluation is that HTML/CSS validation can be fully automated, whereas accessibility evaluation requires a significant amount of subjective judgement. Therefore, the accessibility checkers may give warnings of possible accessibility problems that require students to evaluate their content manually and decide whether it might pose accessibility challenges. In the interest of time, it's ok for students to focus on the errors, rather than the warnings, but they should also be encouraged to consider all the accessibility issues that they've learned about this course, and ask whether any of their content might present accessibility challenges.

Example Output

At the conclusion of Lessons 1 and 2 in this module, students will have corrected any validation errors. When Lesson 3 is complete, they will have added an accessibility review to accessibility.html.