Grade 7 Science Unit 2 Temperature describes how

Grade 7 Science Unit 2 Temperature describes how hot or cold an object is. Chapter 4

Discussion o How does temperature affect everyday life? o What is a comfortable temperature to you? Is it different depending on the person? o How come you can feel cold inside the school sometimes but warm outside while playing hockey on the ice?

Mini Experiment 2 Brave Volunteers!

Mini-Experiment 4 Beakers! Place one hand in a beaker of cold water 1 min Place one hand in a beaker of hot water 1 min Place your hands in the mystery temperature water o Volunteers estimate the temperature of the water in each beaker o Measure the actual temperature with a thermometer o Were you close? o o

Mini Experiment o Why do you think there was discrepancies (differences) between their estimates and actual temperatures?

Discussion o We can’t just say something is ‘hot’ or ‘cold’ – because it is subjective o Scientists need a standardized way to measure temperature

Temperature o Temperature: (general definition) - How hot or cold something is.

Temperature is important everyday, everywhere! o How are you going to dress for the day? n daily temperature changes o cooking temperatures o Refrigeration temperatures o average temperatures in different geographic areas

Activity - predict and identify the temperature! o Cards have either an object/event or temperature o Step one: Get in groups of four. Match the temperature/object card to the correct temperature – CHECK! o Position them in order from cold to warm!

Standard temperatures – to know o The human body – 37ºC o Boiling point of water – 100ºC o Freezing point of water – 0ºC o Comfortable room temperature - ~21ºC

Review Questions: Page 119 Q’s: 1, 6, 7 & 9.

We need to standardize temperatures o Scientists in the past worked towards measuring temperatures and creating a standardized temperature scale. n A scale the same all over the world

Past Measuring Devices o 1. Galileo’s Air Thermoscope: As the air heats, the liquids drops and when cooled it rises.

Past Measuring Devices o 2. Early Liquid Thermometer: Liquid rising up the tube shows the temperature is rising.

Create a Classroom Thermoscope o Page 121

Temperature Scales o Scales are necessary for temperatures to be accurate and comparable. o 3 Types: n Fahrenheit n Celsius n Kelvin

Fahrenheit o first widely used measuring scale for temperature o developed by Daniel Gabriel Fahrenheit

Celsius o Scale based on the freezing and boiling points of water. o Developed by Anders Celsius

Kelvin o Scale starts at the coldest temperature possible - absolute zero (-273 o. C). o Developed by William Thomson (Lord Kelvin)

Scales Comparison

Interactive Matching Game o http: //funphysics. jpl. nasa. gov/advent ures/temperature-game. html

Interactive 2 – Build your own temperature scale! o http: //wwwtc. pbs. org/wgbh/nova/assets/swf/1/t emperature-scales/temperaturescales. swf

Measuring Devices 1. The Liquid-in-glass Thermometer 2. Thermocouple 3. Resistance Thermometer (digital thermometers) 4. Bimetallic Strip (thermostat) 5. Infrared Thermometer (thermogram) n Bimetalic strip demo and measuring devices stations

The Liquid-in-glass Thermometer o Description: liquid rises as temperature increases n The lab thermometer contains colored alcohol o Use: Used in the Science lab

The Thermocouple o Description: Made of two different metals. o Temperature change make a current that is read on a meter o Use: Measure high temperatures in a lab and in diesel engines

The Resistance Thermometer (digital thermometers) o Description: temperature is taken through a probe in shows up as a number o Uses: Home use but also in businesses

Bimetallic Strip (thermostat) o Description: Made of two different metals fused together. o These metals expand contract causing the strip to bend when heated. o Use: In thermostats