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

Discussion How does temperature affect everyday life? What is a comfortable temperature to you? Is it different depending on the person? 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 1min Place one hand in a beaker of hot water 1min Place your hands in the mystery temperature water Volunteers estimate the temperature of the water in each beaker Measure the actual temperature with a thermometer Were you close?

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

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

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

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

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

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

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

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

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

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

Create a Classroom Thermoscope Page 121

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

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

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

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

Scales Comparison

Interactive Matching Game http://funphysics.jpl.nasa.gov/adventures/temperature-game.html

Interactive 2 – Build your own temperature scale! http://www-tc.pbs.org/wgbh/nova/assets/swf/1/temperature-scales/temperature-scales.swf

Measuring Devices The Liquid-in-glass Thermometer The Thermocouple Resistance Thermometer (digital thermometers) Bimetallic Strip (thermostat) Infrared Thermometer (thermogram) Bimetalic strip demo and measuring devices stations

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

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

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

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

Infrared Thermometer (thermogram) Description: Shows heat as colors Use: To show heat loss in houses or illness in bodies

Review Questions: Page 131 Q’s: 1, 3, 4, 6, 11 & 12.

Chapter Review Questions: Page 132-133 Q’s: 1, 3, 4, 6, 11 & 12.