flexbooks.ck12.org

Main Information

ℹ️

Title: K-12 FlexBooks | CK-12 Foundation

Description: CK-12’s free, standards-aligned, digital textbooks are customizable, integrated, and interactive, allowing users to create 200,000+ localized FlexBooks.

Keywords: empty

Page Encoding: utf-8

Page Filesize: 296 KB

Server Information

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IP: 3.164.68.58

Location: United States,US,,,37.751,-97.822,America/Chicago

Http Server: apache/2.4.58 (ubuntu)

Encoding: utf-8

Meta Tags List

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property: og:site_name itemprop: name name: author content: CK-12 Foundation
property: fb:app_id content: 159884644067996
itemprop: url content: https://www.ck12.org
itemprop: telephone content: (650) 494-1302
charset: utf-8
name: viewport content: width=device-width, initial-scale=1, minimum-scale=1.0
name: google-site-verification content: wHx0f-Udlfd7ZNYNrIXpJVpjjO8nSH5RE0jIX8V-jIM
name: google-translate-customization content:
name: application-name content: CK-12 Foundation
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name: msapplication-TileImage content: //static.ck12.org/assets/favicon/web-app-manifest-192x192.png
property: og:description name: description content: CK-12’s free, standards-aligned, digital textbooks are customizable, integrated, and interactive, allowing users to create 200,000+ localized FlexBooks. helmet: true
property: og:url content: https://flexbooks.ck12.org/flexbooks/student/
itemprop: provider content: CK-12 Foundation
itemprop: name
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itemprop: url content: https://flexbooks.ck12.org/flexbooks/student/

Internal Links

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External Links

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Whois Information

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domain_name: ck12.org

update_date: 2025-08-07T22:10:54.892Z

update_time: 1754604654

creation_date: 2006-12-16T08:37:03.681Z

creation_time: 1166258223

expiration_date: 2028-12-16T08:37:03.681Z

Whois Raw Data

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            Domain Name: CK12.ORG
Registrar: Amazon Registrar, Inc.
Domain Status: client delete prohibited
Domain Status: client transfer prohibited
Domain Status: client update prohibited
Registry Expiry Date: 2028-12-16T08:37:03.681Z
Creation Date: 2006-12-16T08:37:03.681Z
Updated Date: 2025-08-07T22:10:54.892Z
Name Server: NS-1136.AWSDNS-14.ORG
Name Server: NS-161.AWSDNS-20.COM
Name Server: NS-1687.AWSDNS-18.CO.UK
Name Server: NS-977.AWSDNS-58.NET
REGISTRAR Contact: Amazon Registrar, Inc.
>>> Last update of RDAP database: 2026-02-16T21:03:58Z

SEO Audit

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Technical SEO

✓

Response Code

200

Status 200 OK - page loads correctly.

✓

Character Encoding

Page: utf-8, Header: utf-8

Character encoding consistent between HTML and headers.

✓

Page Size

303246 bytes

Page size acceptable for fast loading.

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Resources

109 total

Too many resources. Optimize and combine files for better performance.

✓

Hreflang Tags

0 hreflang tags

Add hreflang tags if you have multilingual content.

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Robots.txt

Missing

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Sitemap

Not found

Add sitemap.xml and reference it in robots.txt.

✓

HTTPS

Yes

Secure HTTPS connection enabled.

✓

Compression

gzip

Gzip or Zstd compression enabled for faster loading.

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Caching

Not set

Add cache-control headers to improve loading speed for returning visitors.

✓

Page Speed

2.64 ms

Excellent loading speed.

On-Page SEO

✓

Title

K-12 FlexBooks | CK-12 Foundation

Good title length (30-60 characters).

✓

Meta Description

CK-12’s free, standards-aligned, digital textbooks are customizable, integrated, and interactive, allowing users to create 200,000+ localized FlexBooks. Lenght:152

Good meta description length (100-160 characters).

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H1 Heading

2 found - "Interact with Your Math & Science Textbooks in a Whole New Way"

Use only one H1 heading per page. Remove extra H1 tags.

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Word Count

202

Content very short. Aim for at least 500 words for better SEO.

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Canonical Tag

Add canonical tag to prevent duplicate content issues.

✓

Duplicate Meta

[]

No duplicate meta tags found.

✓

Keywords

empty

Meta keywords set (note: not used by major search engines).

Content and UX

✓

Language

en

Language attribute properly set.

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Images

67 total, 51 missing ALT

Add ALT text to images for accessibility and SEO.

✓

Viewport

width=device-width, initial-scale=1, minimum-scale=1.0

Viewport meta tag properly set for mobile devices.

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Open Graph

Missing: og:title, og:image

Add missing OpenGraph tags for social media sharing: og:title, og:image

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Structured Data

1 JSON-LD scripts

Structured data (JSON-LD) found.

Search Phrases - Google

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Position	Phrase	Page	Snippet
3	k e q	/cbook/ck-12-chemist...	Equilibrium Constant (Keq) The equilibrium constant (Keq ) is the ratio of the mathematical product of the concentrations of the products of a reaction to the mathematical product of the ...
7	write 6 6 3 4	/cbook/ck-12-cbse-ma...	Divisibility Rules for 2, 3, 4, 5, 6, 8, 9, 10 and 11 A number is divisible 6 if it is divisible by both 2 and 3 . Example of divisibility rule for 6 : Consider the number 47394. Since its units digit is 4 , it is ...
9	types of energy	/cbook/cbse-physics-...	Forms of Energy - Defintion, Types, Formula, Examples ... The six forms of energy include mechanical, chemical, electrical, light, thermal, and sound energy . Another form of energy is nuclear energy.
12	science models	/cbook/ck-12-middle-...	Scientific Models Models allow scientists to work with systems that are nearly impossible to study as a whole. Models help scientists to understand these systems.
14	write the time using words	/cbook/ck-12-first-g...	Time Conversion between Words and Numbers We are going to learn how to write down the time in digits (numbers). ... The most common way to express time in words is just to say the time in the form HOUR ...
22	us class us	/user:coachtgj/cbook...	The American Class System Most sociologists use six class divisions when describing the American class system. Because it is an open system, people are able to move between classes.
22	date mark time 40 minutes	/cbook/ck-12-middle-...	Elapsed Time Elapsed time is the amount of time that has passed between two events. You can calculate the elapsed time by figuring out the difference between the start and ...
26	complete a square	/cbook/ck-12-algebra...	Completing the Square When the Leading Coefficient ... Step 1: Write the polynomial so that and are on the left side of the equation and the constants on the right. Step 2: Pull out from everything on the left side.

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