Saturday, 4 July 2015

y = mx + c (part 2)

Since the sketch I shared in my first post focused on linear graphs, I thought I would continue with this theme and share some ideas of how I might choose to develop this topic over the next few posts. Once students have a handle on how m and c affect linear graphs, here's a fun game they can play. If they have access to a laptop, tablet or even a smart phone then using a graph plotter is a good way for them to check their answers as this way they can see what's gone wrong if they make a mistake.

Each player needs a set of the cards (A-F) in a pile (I get them to cut their own out first). Playing in pairs or small groups students should all turn over the same card at the same time and try to write down the equations of all of the lines on it. Once each team member has written down their predictions or after an agreed time has elapsed the group can use a graph plotter to check if their equations are correct. One point is scored for each correct c value, one for each correct m value and one for an equation in the form x = a.  There are six rounds of the game and then early finishers can try and design some interesting cards of their own. The cards can then be stuck in books and annotated to explain any misconceptions.

If each group has access to a tablet or laptop a convenient way for students to access GeoGebra is via the new Chrome App (at the sign-in panel thy can click continue without signing in) . For this exercise they should select the algebra view and all they need to do is type in their equations in the left-hand panel. Once they have completed a card their equations can be selected and deleted to clear the screen.

At a push students can use the Chrome App on a smartphone but Desmos which is an online graphical calculator has a much friendlier interface for small screens. Desmos is actually pretty sophisticated; if you start typing an equation into Desmos such as 'y = mx +c ' it will give you the option to set m and c up as sliders as in GeoGebra. Getting students access to laptops or tablets isn't always easy in my school so if I just want students to plot something up I usually get them to use Desmos. I know pupils in many schools now have access to tablets in every lesson -  I'd love to experiment with this in maths - I can imagine it would revolutionize the way I teach.

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