Anytime there is a chemical reaction and energy is released, there is an increase in temperature. As the chemicals come together, the components of each begins to alter and speed up on a cellular level. This causes friction, and friction causes heat.
The vinegar and baking soda provides an example of an acid-base reaction (of chemically-reactive agents), and the combination gives off a gas: carbon dioxide. As it magnifies, it needs to escape, which forces a small "explosion" of energy.
It is also important to remember that the CO2 gas that is created takes up more space than the solid baking soda and liquid vinegar!
When the two ingredients are introduced to one another, the chemical reaction does create an increase in temperature. The reaction lasts only a very short time ("less than a minute") during which the temperature decreases radically.
This is an example of an endothermic reaction, one that needs heat to make it happen.
With the increase of space taken up by the chemical reaction, and the energy that is released in combining the gases, students will enjoy watching volcanoes explode, balloons inflate and maybe even bottle rocket fly.
Yes there is an increase in the temperature because the reaction proceeds as exothermic reaction.