For this coloring page, I would provide warm colors such as yellow and orange for the teacher and students to bring out the atmosphere of learning and knowledge. The chalkboard could be colored in a light blue or teal to give a sense of calmness and focus. The book in the teacher's hand and the text on the chalkboard could be highlighted in a golden yellow to emphasize the importance of 1 September as the day of knowledge, which is the focus of the lesson. Finally, to give the page a complete and vibrant look, I would also use greens and purple to color the walls and other elements. In short, the colors used should provide a feeling of warmth, focus, education and knowledge.