A collection of multiple-choice quizzes for elementary school students: trivia quizzes about everyday things.

12cm

It’s said that hair grows about 0.3–0.4 mm per day, which averages out to roughly 2.5 mm per week, about 1 cm per month, and about 12 cm per year. Since there are about 100,000 hairs on the head and around 90% are in the growth phase, adding up their lengths is said to come to about 100 km in a year. You can see that hair has particularly active metabolism compared to other parts of the body.

Nothing changes.

The color of an eggshell is determined by the breed of chicken—white eggs come from white-egg breeds like White Leghorns, and brown eggs from brown-egg breeds like Rhode Island Reds—so there is basically no difference in nutritional value, taste, or shelf life. However, farms’ specific feeding and raising practices can create differences, so why not try comparing various eggs for yourself?

50km

It’s said that the length of line you can draw before an HB pencil is used up is about 50 km. While this figure assumes certain conditions and isn’t exactly realistic, it’s still far longer than with other writing instruments, making HB pencils arguably very economical.

Sato

Based on government statistics and nationwide telephone directory data, as of October 2023 the most common surname in Japan is Sato, with approximately 1.83 million people. It is followed by Suzuki with about 1.77 million, Takahashi with about 1.38 million, Tanaka with about 1.31 million, and Ito with about 1.05 million.

convenience store

As of 2022, there were 55,956 convenience stores nationwide, compared to 67,886 dental clinics. It’s striking to realize that there are more dentists than convenience stores, which you see everywhere.

3 yen

The 1-yen coin is made of aluminum. The raw material cost per coin is about 0.3 yen, but when you add processing and other expenses, it comes to 3 yen. By the way, it reportedly costs 10 yen to make a 5-yen coin, 13 yen for a 10-yen coin, and finally drops to 12 yen for a 50-yen coin, so try remembering these together.

plastic

There are rubber erasers made from natural rubber and plastic erasers whose main component is polyvinyl chloride resin. Plastic erasers contain plasticizers that give the plastic material elasticity, and thanks to this effect they can erase more cleanly than rubber erasers. As a result, plastic erasers have become the mainstream today.