I have purchased literally hundreds of different brands of laptops for a dozen different schools, so I have a bit of experience in this area.
After considering all the things you mentioned, you should get the HP ProBook X360 435 G9 with AMD Ryzen R5 processor, 13.3 inch touch screen, with 16GB DDR4 RAM. It weighs just 1.45 kg. It has 6 separate processing cores. This machine has the optimum combination of weight, screen size, battery life and processing power that you need. It should last you for at least 4 years if you look after it.