Interactive straight line graph
I have used a spreadsheet with scroll bars to change the gradient and intercept of a straight line graph on a projector as a 'starter' whole class session. I ask students to describe the changes as I click on the scroll bars. You can also set individual work on linking the appearance of the graph to the values of the constants. You can download the spreadsheet which also includes a quadratic as bonus.
I project the spreadsheet and set up Y = 2X - 1
- Ask where the graph cuts the Y axis, and then ask students to estimate the gradient.
- Next, I click on the 'up' triangle on the C slider and ask students what is happening
- What will happen when C goes positive?
- Then I slowly reduce the gradient towards zero by clicking on the M down arrow and ask what is happening. Bumping the down arrow gives an 'animation' effect.
- What will happen when M=0?
- What happens when M becomes negative?
- Students asked to tell me the values of M and C that will give a line that will pass through (0,-3) and (3,0) and so on...
- Wrap up with note taking and sketching for the four main cases (gradient positive, intercept positive...)
- I often get the class 'performer' to operate the spreadsheet - beware left clicking on the scroll bars.
- Differentiation is by directing the questions to students at different levels of confidence.
I project the spreadsheet using Excel's full screen view . You can download the spreadsheet and customise it to suit your needs.
- The scroll bars come from the forms toolbar (View | Toolbars | Forms in the Excel menus).
- You can link the value of a cell to the position of the scroll bar - the value will be a whole number between 0 and 100. There is an excellent article about this on FERL.
- You use a spreadsheet formula to map the interval [0,100] to [-5,+5] or whatever for both the M and C scroll bars
- You build a table of values for Y and X with the M and C cells as constants - you only need two values but using 11 values makes it easier to draw other functions. The table is set up well below the display part of the spreadsheet
- Then use the XY scatter chart in Excel with the join points clicked to draw the graph
- Used for GCSE Foundation and Intermediate work on straight lines
- Quadratic used by colleague with Access level 3 students to link the solutions of the quadratic with the graph, as well as investigating the role of the a, b and c constants.
- Applicable to vocational areas where extra maths is needed, e.g. construction, engineering and so on.
Originally added on Thursday, April 3, 03
in category: ilt in maths
[ top ]
Use this form to send a comment about this resource. When you send your comment by clicking on the 'Send' button, you will be returned to this page.
[ top ]
Content by Keith Burnett and contributors
Powered by Movable Type 2.63
ilt in maths