Seven Small Inventions That Change The World Written by Roma Agrawal. Reviewed by Emaan, Age 8

Wow! What a bright, intricate and interesting front cover? The drawings are just so colourful and I can’t believe how many inventions there are just on the cover page. My favourite is the Rubik’s cube because I have one and I really like to solve it.

This book is full of so much interesting and new information. It is about seven inventions each unique and special in its own way. I have had so much fun learning about the inventions by reading this book. There was so much to learn so I looked at one invention each day.

I was very intrigued to learn about how nails are made. I did not realise the intervention of the nail led to the invention of screws, rivets and bolts. I love the page that gives details about the different ways in which nails are used. I was surprised to learn that some shoes have nails in. There are lots of other things which have nails such as locks, microscopes, blenders, floorboards, skyscrapers and tunnels! I was fascinated to learn that nails were around during the time of the Ancient Romans and Ancient Romans.

I read that in 1801, Thomas Jefferson who went to become president of the united states set up a factory where enslaved men and children made up to 10 000 nails a day. I was impressed that so many nails were being made each day, but I was sad that it was enslaved children and men making them. Before this nails were made by hand.

I used to think that wheels were only used on transport but then I learnt that wheels are used for other things, for example door knobs, electric toothbrushes, dishwashers, fidget spinners and nibs of ball point pens. I cannot believe that dishwashers have wheels in them. I learnt wheels are hard to design because they need to be strong so they can carry a large weight, but they need to be light too otherwise they will need a lot of energy to move. I was surprised to hear that the earliest wheels did not have spokes, they were made from three heavy planks of wood. I was astonished to hear that if you chip away at the edges of a round wheel to create little teeth, you’ve made a gear. When you put gears together , you can change the direction of rotation and the speed; I did not know that there are gears of different sizes in a clock that turn at different speeds to tell us the hour, minute and second. I have learnt that a lot of components of the International Space Station are based on spinning discs or wheels.

Before reading this book, I knew that my slinky toy and trampoline both have springs and the mattress on my bed. After reading the book, I have discovered many more things that have springs such as bases for microscopes and telescopes, retractable pens, retractable syringes, keyboards and weighing scales.

In school we have learnt about magnets so I was excited to find out more about magnets. I wish I had this book before we worked on that topic because then I would have been a total magnet pro! I knew that cars, radios, telephones and printers have magnets, but I have now learnt about many more uses of magnets like in thermostats, wireless chargers, speakers and maglev trains. I have never heard of these trains before, so that was something else that I have learnt. I can’t believe that the maglev trains float just above their tracks.
I already knew about lots of uses of lenses such as magnifying glasses, binoculars, and camera and know that glasses have lenses, but I have now discovered that car head lights have lenses too. I enjoyed reading ‘trick of the light’ and how optical illusions are created.

I was fascinated to learn about string because I have started to practice knitting and I play the cello.

The final part of the book was about the invention of the pump. I knew about the heart being a pump and balloon pumps, but now I know about other types like the rotary pump, centrifugal pump and diaphragm pump. I had never heard of these.

My favourite invention is definitely the spring. If there were no springs I would not be able to bounce on my trampoline.

This book still has lots of information that I want to learn so I will keep reading it lots of times.
I would recommend this book to everyone interested in inventions and science. I think it would be good to have this book in all school libraries too!