Sensoristic applying field is fascinating, and sometimes sounds magic or something common people cannot approach immediately.
Our body is full of sensors (like ears) able to capture vibrations or other stuff: so you natively have parameters which to confront and start with.
Thermometer is made by a temperature sensor: old types were based on mercury's properties to expand or shrink itself proportionally to sensed degrees.
Electrical thermometers have the equivalent of mercury in temperature sensors.
Here we'll use the LM35DZ analog temperature sensor, whose scale is set directly to Celsius one.
Reading Datasheet and referring to our component in TO-92 plastic package as on second page, we must take care of an important particular: kind of view.
To connect correctly the LM35DZ we have to respect the input pins, knowing that view proposed in datasheet is the bottom one.
Watch out! Reversed could result in a damage for component, because voltage supply goes from -0.2V to 35V (top of third page).