Some shopping malls use high-frequency “mosquito sounds” to stop teenagers from gathering in certain areas. It may sound strange, but the reason behind it is mostly economic. Malls want their space to be occupied by people who will likely spend money. When large groups of teenagers hang around without buying anything, they take up space, create noise, and make the area feel more crowded. This can discourage adult consumers, who usually spend more, from staying longer in the stores. In economics, every part of a mall is considered valuable. The goal is to increase revenue from each square metre. If a space is filled with people who are not contributing to sales, the mall sees that as an inefficient use of resources. Instead of hiring more staff or redesigning the whole area, playing mosquito-frequency sounds is a low-cost method to change customer behaviour. While this method may feel controversial, it shows how businesses use simple tools to manage customer flow and maximise economic efficiency.

Differentiation is the process of measuring how fast a function changes. Some of the readers may have learned it in IGCSE Year 2 Maths. This paragraph will explain deeper about how mathematicians developed the idea behind this concept. On the curve above, point A represents the value of f(x) at x, and point B represents the value of f(x+h) at point (x+h). The straight line (the yellow line) connecting two points A and B is called a secant line. The slope of this line can be calculated by the formula: Gradient = rise/run: ⇒ f(x+h) - f(x)/(x+h)-x ⇒ f(x+h) - f(x)/h This secant line represents the average rate of change between the two points A and B. As h becomes smaller (approaches zero), it means that point B gets closer to point A, and the secant line becomes a tangent line. This process gives the exact slope of a curve at a point, which is called the derivative.

Today’s area witnesses the rapid rise of technology, and AI is gradually considered to replace humans. Some people believe that learning english is no longer necessary since AI is already a great tool for translating and communicating in multiple languages. But for many reasons, AI is still irreplaceable for learning english. First things first, we have to understand now that english has become a global language, things like education, businesses,jobs opportunities,... are all related to this language. Undoubtedly, AI has made communication more easier than ever for us. A simple demand and a few typed words can translate any language into english within seconds. However, learning a language is not just about translating words or remembering the vocabulary, is about developing our cognitive skills and enhancing cultural understanding. Studying english helps our brain to think in various ways, to analyze, to abstract ideas and thoughts to communicate them in a structured. The brain’s memory,problem-solving and cognitive flexibility skills are developed as we learn. Cultural differences are learned through humour, idioms, and social regulations which AI cannot replace. English learning gives a person a wide view and the ability to empathize with people from different countries. AI may translate the world accurately, but it cannot have the cultural value that people us accumulated over thousands of years of history. In general, AI definitely cannot replace the need to learn english. Rather than fear of replacement, we should embrace AI as a partner, a tool that helps us to enhance learning and embrace changes.

Have you ever heard this term before and wonder what exactly is behavioural economics? Classical economics assumes that humans are rational thinkers. They have full access to perfect information, have sufficient time for making the best decision. However, this is not always the case in reality. Humans in real life are considered irrational and act on their self interest. Why? Because, us, a normal human, have different preferences for goods and services. Some people will highly likely to purchase an idol’s album even though this is not the best option for their sake simply because we are really into it. This makes the economic models cannot be applied straightforwardly to real-life settings. In that case, behavioural economics will take place for the explanation. Behavioral economics is defined as a field that integrates psychological principles with economic theory to challenge traditional assumptions of rationality and selfish preferences, emphasizing the role of emotions, decision-making under risk, and the impact of framing on outcomes. In simpler words, it investigates people’s behaviour in the economy, examining thoughts, preferences and irrationality. This plays a pivotal role in how economic agents make their decisions, such as businesses and policy makers. For example, by acknowledging how consumers perceive the value of products, firms might design the best-fit message delivering to their customers. Also, acknowledging human behaviours might aid companies and governments to account for potential risks and suitable modifications. -By Vu Thanh Hao Ngoc 12AL1-

The article “Chocolate lovers, brace yourselves: Prices are rising, but not forever” by Jenni Reid (CNBC, August 22, 2025) discusses the recent surge in chocolate prices caused by harsh weather, pest outbreaks, and resource shortages in Africa, where 75% of the world’s cocoa is produced. Rising production costs and global inflation have further driven up prices, while the supply of cocoa remains inelastic due to limited suitable land and few producing countries like the Ivory Coast and Ghana. Despite high prices, demand for chocolate stays strong, showing price inelasticity on the demand side as well. However, prices might decline next year as cocoa production improves with better weather and maturing crops, though UK retail inflation and US trade policies could keep pressure on prices. Government intervention is not essential since chocolate is not a necessity, but producer countries might subsidise or support the industry if prices hurt competitiveness. The article suggests that investment and technological improvements would be a more effective long-term solution to increase cocoa supply and stabilise prices.