According to https://www.usdairy.com/news-articles/how-much-sugar-is-in-m...

Milk Sugar Content (per 8 oz. serving): 24 grams sugar (12 grams natural sugar, 12 grams added sugar)

According to https://www.nhs.uk/live-well/eat-well/food-types/how-does-su...:

    Adults should have no more than 30g of free sugars a day,
    (roughly equivalent to 7 sugar cubes).

    Children aged 7 to 10 should have no more than 24g
    of free sugars a day (6 sugar cubes).

So one small carton they have at school has 30% of an adult's daily intake of added sugar.