There are various ways to see the action of surface tension.
Cut a small piece of plastic. Take some water in a large tub. Put the plastic piece on the surface of the water. You will see that the plastic piece is not moving. Then you put a drop of detergent soap in the area of the rear notch of the plastic piece. You will notice immediately that the plastic piece is moving forward. This is caused by the lowering in the surface tension caused by the detergent.
Another easily displayable evidence of surface tension is the way water would rise in a very thin tube when its lower end is immersed in water.
You might have seen steam powered toy boats in the toyshops. You can also build something like it at home. All you need is an aluminium container, a small aluminium hollow tube and a few small pieces of candles. Seal one side of the hollow tube with a cork.
Then fill it with water and seal the other side also. Make a small hole on the cork on one side and place it in the container as depicted. Below it, on the sides, place the candles. Place the whole thing in a tub full of water. Light the candles. Once the water in the tube heats up, steam will start emitting into the water in the tub and you will see that the boat is moving.