Summer "Edu-Fun"
For the more relaxed summer months, consider the following summer "edu-fun" learning system.
    
Each child has a 3-ring binder with 10 dividers.  The dividers are labeled as:

Charts
Bible Study
Prayer Journal
Bible Memory
Reading
Writing
Word Use
Science
Social Studies
Math

Charts:
Each child keeps a chart that tracks seven main "edu-fun" categories: Bible Study (which includes Bible Study, Prayer Journal, and Bible Memory); Reading; Writing; Word Use (Spelling, Vocabulary, Grammar); Science; Social Studies (Government & Citizenship); and Math.  (Multiple charts will need to be printed for each child to last through the summer.)  As a child finishes a category each day, he/she places a sticker (or checkmark) in the appropriate box. 

WORDPDFChart

Bible Study:
Have your child study a topic of his/her own choice.  The topic can be a specific book of the Bible, a topic like "praise," a Bible person like Daniel, and so on.  The point is, it is a topic that the individual child chooses to study.  Using the concordance, the child looks up a Bible passage that has to do with the chosen topic.  He/she studies that passage and journals his/her notes.  If your child needs more guidance than "study a topic of choice," you can assign a passage that you have selected. 

WORDPDFBible Study Journal

Have your child keep a prayer journal using the following pages.  Each child has one packet of all the pages stapled together and placed in the inside left pocket of the binder (for reference).  Then, a new copy of only page 2 is filled out each day by the child and placed behind the Prayer Journal divider.

WORDPDFPrayer Journal

Have your child memorize a new Bible verse each week (of your choice or the child's choice).  Your child will place a copy of the week's verse behind the Bible Memory divider for easy reference. 

Reading:
Have your child read a book of his/her choice.  As the parent, determine how many minutes qualify for a reading sticker for each child.  Some nice  reading logs can be found at http://www.countryclipart.com/ReadingLogs/readinglogs.htm.

Writing:
Have your child choose a writing activity, such as:  writing in a personal journal, writing a creative short story, or even working on a writing worksheet.

WORDPDFSentence/Picture

WORDPDFParagraphs

WORDPDFEssays

Word Use (Spelling, Vocabulary, Grammar):
Daily, each child uses a dictionary to pick a new word of his/her choice.  The only requirement is that the word must be "new" to the child (the spelling and/or the meaning).  They will each log the new words on a Word Use Worksheet. 

WORDPDFWord Use Worksheet

Science:
Have your child choose a science activity, such as:  keeping a nature journal, using a microscope and keeping a journal of observations, doing a simple science experiment.  For experiments, here are a few sites to check out:

http://www.exploratorium.edu/science_explorer/index.html
http://www.kidzone.ws/science/
http://scifun.chem.wisc.edu/HOMEEXPTS/HOMEEXPTS.html
http://www.tryscience.org/experiments/experiments_home.html
http://www.sciencebob.com/experiments/experiments.html
http://www.energyquest.ca.gov/projects/index.html#electricity
http://www.gourmetgiftbaskets.com/Kitchen-Scientists-Home-Experiments.asp
http://polymer-search.com/top-science-project-ideas.html
http://www.designerappliances.com/articles/a-home-guide-to-kitchen-science-experiments/ (Thanks to Jamie and Sam!)
http://www.berkeyfilters.com/articles/science-experiments-with-water-/
(Thanks to Michelle and Abby!)

DISCLOSURE NOTICE:  I have not looked at every experiment in the above sites.  As always, use your judgment as to whether an experiment is appropriate for your children.  Also, I did not see any experiments with evolutionary teaching, but that doesn't mean there aren't any.  Finally, be sure to supervise your children when they are doing the experiments.

Social Studies (Government/Citizenship):
Consider focusing on government and citizenship during the summer months by choosing activities from the following website:

http://bensguide.gpo.gov/index.html

Math:
Have your child complete refresher math worksheets and/or math teasers and puzzles.  Here are several websites with free math worksheets: 

http://krazydad.com/sudoku/
http://abcteach.com/directory/basics/math/#directory
http://superkids.com/aweb/tools/math/
http://www.aplusmath.com/Worksheets/
http://themathworksheetsite.com/