Invisible ink project

Here is the first project which is: Invisible Ink!!!
Materials needed:
 .1 Lemon
 .Small Cup Of water
 .A Spoon
 .A dish
 .Ear cotton
 .Some papers to write on

Procedure:
1-Cut off the lemon and squeeze it in the dish.
2-Pour some drops of water in the dish.
3-Mix the water and the lemon in the dish using a spoon.
4-And now you have the invisible ink.
5-What to do now is put some drops of it on the ear cotton and use it as a pen to write on a paper.
6-Write whatever you want and then when you need the words to become clear to read, just put the paper facing the sun for a few minutes and see the words you have written!!!