This is an interesting question. We need to find a topic that uses different numbers to represent different numbers, which is suitable for junior three students. In this topic, we need to use some simple figures, such as circles, squares and triangles, to represent the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 respectively.
First, we can use a circle to represent the number 0, a square to represent the number 1 and a triangle to represent the number 2. Then, we can combine these figures to form some simple patterns, so that children can guess the numbers they represent by observing these patterns.
For example, we can draw a pattern consisting of two circles and a square, which can represent the number 12. Similarly, we can draw a pattern consisting of two triangles and a square, which can represent the number 24.
In order to make children understand this topic better, we can give them some examples to let them know how to combine figures to represent numbers. Then, we can let them play freely, draw some of their own patterns and ask them to explain what numbers these patterns represent.
Through this topic, children can not only exercise their observation ability, but also learn how to combine different elements to create new things. In addition, they can learn how to explain and express their thoughts and ideas in their own language.
Besides using numbers to represent numbers, we can also expand this topic in other ways. For example, we can let children use different colors or shapes to represent different numbers. Similarly, we can also let them try to use some more complex graphics to represent numbers, such as a circle with a square inside, representing the number 10 and so on.
In a word, this is a very interesting topic, which can let children learn mathematics knowledge and exercise their observation ability and creativity in games.