How can you prove that the stem grows near the top?

In order to prove that in plants the stem grows near the top, you can use various methods. For example, you can paint parts of the stem of a plant in different colors: the bottom of the stem in one color, the middle in another, and the top in a third. It is necessary to measure the boundaries of the flowers, write down the values and also measure the total height of the plant. After a certain amount of time, when growth occurs, you can see which part of the plant has changed, which color has become “longer”, and which parts have remained unchanged.