Looking for free educational software that can help increase the productivity of your classroom? The Internet is a great place to find free, downloadable software for teaching, collaboration, online conferencing, and much more. Here are 15 education-related software products to try throughout the school year:

Mindomo - Mindomo is free mind mapping software that can be used to organize and iron out ideas. It works extraordinarily well for classroom projects.

GeoGebra - This award-winning math software is designed for all education levels. The software is built to handle variables, vectors, points, derivatives, and much more.

WordWeb - WordWeb is a free English dictionary and thesaurus that can define words in almost any program. The software works as a thesaurus and dictionary for British, American, Canadian, Indian, Australian, and global English.

Zoho - This site provides a suite of free tools that can be used for increasing productivity and organization. Within Zoho, users will find software for writing, spreadsheets, document management, notes, wikis, and much more.

Primap Software - The Primap Software features the MapCreator 2.0 for creating animated and standard maps. This software combines cartography and graphics programming for professional, high quality maps.

Celestia - Celestia offers free, 3D space simulation software that allows you to explore the solar system, stars, galaxy clusters, and more.

VoiceThread - VoiceThread provides free technology for sharing videos, documents, and images in a collaborative way. With VoiceThread, you can present collaborative slide shows that can be commented on with voice, text, audio, and video.

Question Writer - The Question Writer site provides free basic quiz writing software that can be used for creating multiple choice quizzes. The quizzes can be printed or published online with reports emailed to you.

iTALC - iTALC is a powerful didactical tool that can be used for viewing and controlling computers in a network. The software provides remote support capabilities, monitoring, real-time demos, texting capabilities, and computer control.

SugarLabs - Used daily by about one million children, SugarLabs is a great place for finding free educational software. The activities on SugarLabs are offered in 25 different languages and cover a wide range of subjects.

Anki - Anki is flashcard software for studying and learning educational material. This software allows you to review material from anywhere and split cards among students.

Yugma - Yugma is free web conferencing software that allows you to conference with up to 20 people at once. With this software, you can have online meetings, desktop sharing, real-time collaboration, and more. Yugma works with Windows, Mac, and Linux systems.

Audacity - Audacity provides open source sound editing and recording software for Mac, Windows, Linux, and other operating systems. Teachers can use this software to record live audio, convert sounds to digital files, edit, mix, and change any sound.

Phun - Phun is free gaming software that can be used to help students understand and appreciate physics. This fun-based learning software allows users to create machines, games, and much more.

Sheppard Software - Sheppard Software provides a large suite of software designed specifically to aid schools and teachers in geography, math, and vocabulary. Throughout this site, teachers will also find free online games for all subjects.

Guest post from education writer Karen Schweitzer. Karen is the About.com Guide to Business School. She also writes about online classes for OnlineClasses.org.