1. How Atlas Colors Show Height and Land Use
The colors in an elementary school atlas (published by Teikokushoin) are designed to help students read terrain and how people use the land. They use two methods: showing land height through color steps (contour color shading) and dividing land by how it is used, such as urban areas, rice fields, fields, and orchards [3]. In this article, we view colored pencils as similar "tools for conveying information through color." While an atlas uses color to tell the reader something, colored pencils become a tool for choosing colors to tell others. Note that there is no source stating that schools officially define the role of colored pencils this way.
Atlas color coding is convenient, but if it relies only on color, it becomes hard to read for people who struggle to distinguish colors. The atlas uses a trick to make this easier to read, which we will look at in later sections. First, let’s look at a more familiar scene. How are colored pencils used when marking circles in notebooks?
2. Why Red-Blue Pencil Marks Are Chosen for Visibility
A red-blue pencil is a single pencil with two colors: red and blue. An article introducing school supplies based on school newsletters states that red is darker than vermilion, making notebook text easier to see. This makes it good for circling mistakes or color-coding important parts [4]. For example, you can circle a wrong answer in red and write the corrected answer in blue. This way, when reviewing, you can instantly see which parts were corrected. This is just one example; rules for using red-blue pencils vary by school.
Marks circled in red are very noticeable to many people. However, for those who find it hard to distinguish colors, the difference in color may be unclear. So, how many people actually find it difficult to tell colors apart?
3. How Common Is Difficulty Telling Colors Apart?
Materials from the Japan Ophthalmological Society state that innate color vision characteristics (congenital color vision deficiency) are seen in about 5% of boys (1 in 20) and about 0.2% of girls (1 in 500) [1]. Let’s convert these percentages into numbers. If there are 40 boys, about 2 would fit this ratio. If there are 500 girls, about 1 would. People often think it is "1 in 100," but 0.2% is indeed 1 in 500. These are averages, so it does not mean a specific number of students will definitely be in any given class.
The same materials explain that colors are not completely invisible to these individuals. Rather, they may find it hard to distinguish between certain colors, but there is little inconvenience in daily life [1]. The problem arises when information is conveyed using color alone. If you rely only on color differences, some people may not receive the message. So, what tricks do schools use?
4. Why Chalkboards and Atlases Add One More Clue Besides Color
News reports describe a 2003 Ministry of Education, Culture, Sports, Science and Technology guide on color vision. It suggests using white and yellow chalk primarily on blackboards. When using other colors, it advises adding non-color information, such as underlines or boxes [2]. Note that this point is read through news reports, not the original ministry document itself.
Atlases use a similar approach. In land use color coding, green-toned rice fields and fields, and red-toned orchards, have patterns (ground patterns) added to the background to make them easier to identify [3]. This allows distinction by pattern, not just by color. Underlines and boxes on chalkboards, and patterns in atlases, are both tricks that add "one more thing" to color. You can try the same idea when writing with colored pencils. The final section shows how to test this in your own notebook.
5. How to Test Whether Your Notebook Works Without Color
Choose two colored pencils. Write down what you learned today, using the first pencil for "important words" and the second for "words to research." Once written, ignore the colors for a moment. Add an underline to the "important words" and a box around the "words to research." This lets you test if the distinction is clear without looking at the colors. This uses the same logic as underlines on chalkboards and patterns in atlases.
If you want to read the original sources, the Japan Ophthalmological Society materials on color vision are available in reference [1]. The stories about chalkboards and atlases start with references [2] and [3]. The original Ministry of Education document and the full atlas editing intent document can be found on the respective ministry and publisher websites.