Key to Decimals
Key to Decimals is not a complete math course, but it a fairly complete course on decimals for children about ages nine and older. The Key to... books generally have lots of white space and less paper and pencil work required per page than other workbooks. They emphasize concepts with pictures and easy-to-understand explanations rather than drill work. The Decimals series consists of four student workbooks and a teacher's guide/answer key. An optional Reproducible Tests book is also available. The folks at Timberdoodle (who sell the Key to... books) note that the fourth book in the Decimals series requires the use of a scientific calculator (one that shows square roots, pi, etc.) for two pages and also that a calculator will be beneficial in numerous other instances.
Key to Fractions
Similar to the Key to Decimals series, Key to Fractions is not a complete math course, but it is a fairly complete course on fractions for children about ages nine and above. It is particularly useful for students who need extra help with this topic.
The Fractions series consists of four student workbooks and a teacher's guide/answer key. (See Key to Decimals description above.) An optional Reproducible Tests book is also available.
Key to Geometry
Geometry at fifth or sixth grade? Actually, Key to Geometry is only an introductory geometry course, so it can, indeed, be used with students below high school level. Some will be ready as early as fifth grade, while sixth to eighth graders are the most likely users.
Children learn by using a compass and straight edge to create geometric constructions. They learn the principles (theorems) through discovery rather than by having it explained in words. Children learn concepts rather than computation skills.
The format is very user-friendly with lots of white space for drawing and few words. There are eight student workbooks with a total of more than 600 pages; the first six are fairly thin, and the last two are hefty. While it might be used as a year-long course, Key to Geometry functions best as a supplement.
Four teacher's guides/answer keys cover the eight workbooks. Students can work independently with minimal teacher input when they have problems.
Key to Measurement series
The Key to Measurement series features hands-on activities, games, application situations, word problems—a wonderful variety of learning activities. This four-workbook set should be appropriate for children in second grade and above.
Book 1 covers English units of measurement; Book 2 covers measuring length and perimeter; Book 3 covers finding area and volume; and Book 4 covers weight, capacity, temperature, and time.
Second graders should be able to complete Book 1 with help from a parent. The other books will stretch up into higher grade levels. A single teacher's guide with answers covers all four books.
Key to Percents
Children should have covered fractions and decimals before tackling percentage. Since these books are ungraded, they can be used with any student who has covered the prerequisite topics.
This series of three workbooks uses word problems, illustrations, and easy-to-understand explanations to help children understand this very practical topic.
Like the other Key to.... books, the format is user friendly with plenty of white space and few problems per page. A single teacher's guide/answer key covers all three workbooks. An optional Reproducible Tests book is also available.