Abstract
The Cognitive Development Method (CDM) is one of the courses that must be taken by Early Childhood Education (ECE) students at Universitas Terbuka (UT) as their core competency. Learning materials in printed books and as many as 12 modules were prepared to facilitate students' learning independently. Today's rapid digital development demands learning materials that are more attractive and interactive for students. Moreover, the average age of ECE-UT students includes the millennial generation. One of the efforts to make it easier for students to learn is redesigning CDM printed books into interactive digital books. This study describes the field-testing results of digitally redesigning CDM books' appearance. The research method used is Research & Development. The display is more colorful, with more examples and pictures, and they can access relevant video enrichment. The field testing was applied to 377 ECE-UT students. The field-testing results showed (scale 5) that the attractiveness of shape, font size, and layout was rated 4.1. The color composition is still rated 4. The improvement suggestions submitted by students are about color composition to make it more attractive, the font size, the explanation of the material, and the appearance of the module cover to be made more attractive and created for each module, and digital books can be downloaded if possible. The study concludes that CDM's interactive digital book is adequate but must be refined according to user input.

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