I have a friend who is a maths teacher and she has asked me to find a place
where she can download free lesson plans. NOT software but
pre-prepared ideas for lessons possibly in the form of popular MS
application files eg a powerpoint presenation. I have tried a regular
search in Google and there appears to be plenty of ideas but little in
the way of downloadable files. If there is anything out there then the
preference would be for lessons plans suitable for secondary education
in the UK.

Unfortunately there is not as much as one would hope for in regards to
pre-pared lesson plans available for download online. While there are
a plethora of teaching websites and resources, only a few have
detailed lesson plans of any worth and only a couple more have items
available to be downloaded to assist those lesson plans.

There is one resource that has several Microsoft PowerPoint
presentations for Mathematics. Cyber Exchange is a teacher's resource
and their archive of Math PowerPoints can be found at
http://208.183.128.3/ce/ppt6-12math.htm

Another good source is ExplorASource. They offer materials for a
variety of topics in Mathematics for grades K through 12 in several
different formats.
"Find cross-referenced instructional resource materials and
educational standards that meet the needs of your students or
children.
The educational resources referenced in ExplorAsource include: Books,
Software (CDs), Videos, and Web sites"
http://www.explorasource.com/cgi-bin/WebObjects/explorasource

A third source to check out is The Explorer.
Explorer
"The ExplorerTM is a collection of educational resources
(instructional software, lab activities, lesson plans, student created
materials ...) for K-12 mathematics and science education. You may
browse through mathematics and science education curricula (we plan to
expand to other curricula) or conduct searches that focus on specific
interests. Many resources are available in the Adobe Acrobat format
that is readable by Macintosh, Windows and other OSs."
http://explorer.scrtec.org/explorer/

Hopefully this will provide your friend with new resources for
teaching mathematics.


Additional information:

Math Central: Resource Room (Secondary Level)
http://mathcentral.uregina.ca/RR/RRbrowse.sec.html

The Math Forum @ Drexel: Education Materials Directory
http://mathforum.org/library/resource_types/ed_mats/

DMOZ: Math: Education: Lesson Plans Directory
http://dmoz.org/Science/Math/Education/Lesson_Plans/

Google Directory: Math Lesson Plans
http://directory.google.com/Top/Science/Math/Education/Lesson_Plans/

Public Discussions at The Math Forum
http://mathforum.org/discussions/

Math Central
http://mathcentral.uregina.ca/index.html

Teacherline: Virtual Mathematics Academy
http://teacherline.pbs.org/teacherline/academy/virtual.cfm


Search terms used:

"math lesson" download
://www.google.com/search?q=%22math+lesson%22+download

"math lesson" powerpoint
://www.google.com/search?q=%22math+lesson%22+powerpoint

there are several lessons plans including downloadable PDF worksheets at:

    http://www.picciotto.org/math-ed/

hope this helps...