You can use rubber bands to model single, double and triple covalent bonds by comparing the force needed to stretch one, two or three rubber bands at once. In doing so you will observe that triple bonds are the strongest, double bonds are the next strongest and single bonds are the weakest. It's harder to stretch three rubber bands at the same time than it is to stretch two, and it's easier to stretch a single rubber band.
A single bond consists of one pair of electrons being shared between two atoms. A double bond is two shared pairs or four electrons, and a triple bond is three shared pairs or six electrons. Triple bonds are the shortest and single bonds are the longest.
The strength of a chemical bond is indicated by the bond dissociation energy, which is the amount of energy required to break the bond. The example below of bond dissociation energies of bonds between carbon atoms verifies the relative strengths of the types of bonds:
carbon-carbon single bond: 350 kJ/mole
carbon-carbon double bond: 611 kJ/mole
carbon-carbon triple bond: 835 kJ/mole