What is a preposition of place? It is a word that connects two nouns and tells you the position of the one thing and the other. Let's look at an example.
In and inside
Here Tara is visiting the zoo. She sees a tiger in a cage and a walrus in a cage. When we use the preposition 'in' we know that the thing after 'in' (the cage) is all around the noun that comes before the 'in' – the tiger and the walrus. Now, to get to the zoo Tara was in the car, like the animals are in the zoo - because the car and the zoo are all around them.
Sometimes, when we want to be very clear that one thing is 'in' another we use an even stronger preposition of place, and say 'inside'. If we look at this box we can see that there are two kinds of side. There are the sides that are in and the sides that are 'out'. So something in the box is on the 'inside'. You can be in things that are not box-shaped. Here we see Tara in black jeans watching a pelican in the water. The reptiles and insects are inside this building.
So when we use 'in' or 'inside' we know that the noun before 'in' or 'inside' is around the thing that comes after the preposition. Like here, where the spider is inside the glass cage, or not inside the glass cage. By using prepositions of place, we know the position of the spider and where the cage is. This might be important. Be careful Tara.
When we use 'in' the thing that is inside does not need to touch the sides of the thing it is in. Here Tara is in a room watching the reptiles, but she is not touching the walls.
On and off.
When we want to say that something is touching something else, we often use 'on'. Often the thing before 'on' is on top of the thing after the preposition of place. For example here, Tara is on a bicycle,with Tara coming before 'on' and the bicycle afterwards. Now, can you see the difference between 'on a bicycle' and 'in a car'? That's right, when you are in a car, the car is all around you. But when you are on a bicycle you are on top of the bicycle. Here's another example. Tara is on the bed; now she is in the bed. Do you see the difference?
Often when something is 'on' something else it is on the top, like the food on the table, and the hat on Tara's head. However it doesn't have to be on top, you also have shoes on your feet, a clock on a wall and leaves on a tree. You can even have glasses on your nose. So 'on' does not always mean 'on top of'.
When you understand 'on' you can understand 'off'. 'Off' is when something was 'on' but isn't any more. So Tara takes her hat off when she comes back home, and in autumn the leaves fall off the trees. Watch Tara as she gets on her bicycle and gets off again.
In the modern world there is also a special meaning of 'on' and 'off' for machines. When a machine has power to go, we say it is 'on' and when we take away the power, we say it is 'off'. To watch her favourite program, Tara has to turn the TV on, and when she has finished watching, she turns it off again.
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