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The Number line tool has been developed as an easy-to-use resource in which you and your students can quickly explore a range of statistical calculations and graphs from small scale data sets.
It is not intended to handle large data sets for which other ICT resources are more appropriate.
The environment will support a range of thinking skills which underpin rich mathematical activities and will help students to:
- Understand mathematical notation
- for example, how the fractions 17/20 and 0.85 are related to each other
- Develop a need for mathematical conventions
- for example, why we have to make a decision about what to do with the digit 4 in 23.45 if we round the number to one decimal place
- Make and test conjectures
- for example, predict where on the Number line a will be less than n if they are related by the equation a = n X -2
- Develop a fascination with our number system
- Explore independently the relationships within and between numbers
Entering a set of data Number line
When you launch the tool, you will be prompted to define your Number line by entering a minimum and maximum value. Twenty numbers will always appear on the line. You define the number of marks between each number by entering a value in scale marks.
At this stage you will want to consider the most appropriate numbers for your students and whether you are working within the range of positive and/or negative numbers or both and whether you require decimal or fractional representation.
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Entering these numbers:
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Would give the following Number line:
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Whereas, choosing
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Would give this Number line.
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If you wish to hide the fractions you can do so by un-checking the check box “Fractions” under the Settings tab. This also works for “Numbers” and Point a, b and c.
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The decimal value of point n is displayed above the Number line when you start to drag point n along the Number line
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It will be displayed to the number of decimal places chosen when the Number line was created.
With your Number line created, if you now click and drag the point ‘n’ it will move freely along the Number line.
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Using a second point to introduce variables
It is very straightforward to be able to position a second point, say a, on the Number line that is related to the movable point n.
Begin with a simple Number line with integer values, no scalemarks and an accuracy of one decimal place. Hide the value of n.
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To introduce another point on the line that is dependant on the value of n, select Settings and switch on one of the points (a, b or c).
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You will then be able to edit the point by going to the “Add Function” tab The calculator screen shows the rule a = n – 2 being defined.
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When you select ok on the calculator screen and select the “Show Line” tab, the second point will be displayed on the Number line.
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Be aware that the new point may not be visible on the Number line if its value is outside of the range of numbers! You will need to drag n to try to find it! Take advantage of this feature by encouraging students to “troubleshoot” where the point has gone!
Only the point n can be dragged – you can ask students to consider why this might be the case? (a is the dependent variable and is “driven” by the point n).
The values on n and a can be revealed and hidden, as required.
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There are a range of functions supported by the Number line which are:
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Calculator Key
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Definition
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Example
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neg
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negation
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a = neg n would mean a = -n
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^
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exponentiation “to the power of”
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a = (n-2)^2
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sqrt
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square root
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a = sqrt(n) would return the positive square root for positive values on n.
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sin cos tan
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trigonometric functions
sin
cosine
tangent
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a = sin(n)
If the calculator is in Degrees, very little movement will be seen on the Number line. To explore trigonometric functions in more detail, switch to Radians.
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round
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Rounds a function to the nearest integer.
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a = round(n)
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abs
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absolute
Finds the “magnitude” of the function.
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a = abs(n)
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log
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logarithm to base 10
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a = log(n)
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