Negative Numbers

Objectives

To learn that numbers on a number line do not stop at zero but continue away from zero to the left as negative numbers.

To recognise the symbol ‘-‘ in front of numbers when they are negative.

Resources

Abacus 4 Textbooks 2 & 3 | Thermometer (if available) or Internet/virtual thermometer | Squared paper | Introducing Negative Numbers (MyMaths) | Interactive Thermometer (MathsIsFun)

Today's Lesson

Main Activity

As the mental warm-up turn to page 86 in Abacus 4 Textbook 2. Ask your student to complete the page orally.

If you have available a thermometer which includes negative numbers, show this to your student to look at. Otherwise, go to the Internet and search for images of thermometers whose scales include negative numbers. You could use Interactive Thermometer (MathsIsFun)

Talk about counting with your student. So far, you have always stopped at zero, but zero is not the last number on a line when counting back. Run through the activities on Introducing Negative Numbers (MyMaths) . Numbers continue downwards from zero on a number line, just as they do counting up. These are negative numbers, so called because they are less than zero. Numbers less than zero all have a ‘–‘ symbol in front of them, for example:

-7 (read as ‘minus seven’ or ‘negative seven’)

-54

-0.5

Draw a number line for your student to label, ranging from -10 to 10, with 0 in the middle.

Explain to your student that in terms of temperature, the freezing point of water is 0ºC, or zero degrees Celsius. Anything colder than this (in degrees Celsius) is expressed using negative numbers.

Turn to page 10 in Abacus 4 Textbook 3.

Watch 'Negative Numbers'.

Look at the information together and ask your student to copy and complete the first section of the page, then to answer the word problems in the second section.

Then look at the problems. Ask your student to read them aloud and to identify the measurements on the thermometer. It can be confusing for the first time to see the digits getting smaller, as the temperature increases. That is why it is so important that your student uses the visual aid of the thermometer diagram on the page. Support your student as they answer the questions on page 10.

Citations

[1] app.mymaths.co.uk [2] www.mathsisfun.com