It's not easy to find a picture book that teaches the fundamental concepts of math rather than simply listing arithmetic drills. In that sense, finding a series that covers counting, shape exploration, measurement, and the concept of time is truly a lucky find. On top of that, the original English text is included alongside the Korean, giving readers a wonderful two-for-one learning opportunity. All four volumes combine exciting storytelling with a variety of fun activities that help children understand and grow to love the basic concepts of math. Book 1, 'Pirates at Sea,' is about counting. The story opens with a calm sea, its gentle waves hinting that something is about to appear. Remembering the title, children look around for the pirates and get to explore the meaning of the numbers 0 through 10. Watching each pirate with their own unique number is another fun visual element. Through simple, easy English sentences like "Line up!", "Someone's missing," and "How many blue fish are there?", children naturally pick up counting as well as the concepts of addition, subtraction, and pairs. Book 2, 'Aliens and Astronauts,' explores the relationship between flat shapes such as circles, triangles, rectangles, and squares, and 3D shapes such as spheres, pyramids, cuboids, and cubes. The story follows the main characters on a mysterious space adventure as they land on a planet and meet alien creatures shaped like various three-dimensional figures, discovering shapes scattered throughout the universe. This story helps build problem-solving skills through mathematical thinking. Along the way, children encounter vocabulary like planet, shooting star, and footprint, plus a variety of English sentences related to shapes. Before learning to measure objects precisely with a tool like a ruler, math education also includes learning to estimate size by eye. In Book 3, 'Knights in Armor,' children learn in a fun way about size, weight, distance, and length, as well as how to estimate and compare the capacity of containers based on the amount of food they hold. The story takes place in a bustling castle during a knights' skills competition. Be sure not to miss the young page boys busily fitting ten knights of all different sizes with armor, weapons, and horses, along with the cook preparing a feast, the gatekeeper, and the ladies of the court. Each page also features a hidden picture game like 'I Spy...' and 'Find something...', adding extra fun to the reading experience. Children naturally encounter everyday English phrases like "Time to get dressed!" as well as descriptive adjectives for appearance such as gigantic, tall, wide, old, tiny, short, thin, and young. The final book in the series, Book 4, follows five explorers on a safari adventure that teaches time and numbers. Titled 'Explorers on Safari,' this book tackles what is often the hardest concept for children to grasp: telling time. Especially today, with children exposed more to digital clocks than analog ones, more and more kids struggle to read a traditional clock face. Perhaps for this reason, the illustrations show both analog and digital clocks displaying the time. The team of explorers—the expedition leader, a flustered assistant, a cook, and two teammates named Slowpoke and Speedy—set off in search of a giant gorilla. Along the way, children learn to distinguish between morning, noon, afternoon, evening, and night, as well as how to read a clock, understand the order of daily activities, and learn the days of the week—building their understanding and use of time-related vocabulary. Through the original English text, children will encounter phrases such as "Time to get up!", "Breakfast is ready!", "Any questions?", "Who is ready to go?", "Everyone is ready!", "Time to move on," and "Look out!"