The calculator that only thinks if you do!
So we have just invested in a few of these
Qama calculators to play with. I think I just needed to see one for myself and see how it worked. The basic logic is really quite simple. You enter a calculation and press 'equals'. Then the cursor moves to a new line where it expects you to make an 'estimation' for the answer. If the calculator is happy with your estimation,then it will give you the actual answer. If it is not, then you must try again. What a beautiful idea! It has clearly been a terrific effort from conception and design to manufacture and distribution and these are now really easy to get hold of a relatively inexpensive. The question is to think really carefully about how we might choose to use them in mathematics education. There are a few questions that people might think about...
On investment

Would we consider a wholesale swap and ask all our students to get one of these?

Would we like a situation where students had one of these alongside anoher traditional calculator?

Would we go for something like a class set that can be brought out for particular activities?

Is it just something we might recommend for some students?
Well, my usual take on something like this would be option 2, because this leaves all options for use open. You would need to be pretty certain that they were going to get used before you asked parents or schools to make an investment.
On activity
If this was the default calculator, then we imagine that there would be long term improvement in estimating ability and the asociated number sense, but it is worth thinking about the implications. Calculators are often a bridge that allow an activity to focus on particular skills without letting calculating skills hinder progress.

Would permanent use of these calculators slow down activity? Does that matter?

How would we adjust our teaching style to accomodate for the extra stage of involvement?

What would be the implications fo increasing the emphasis on estimation from an early stage?

Is there potential for thinking about specific activities that might make the best use of this calculator?
I think there is a need for experimentation here and possibly picking a class to trial them with one way or another. The first question here helps me answer the first one above, in that I dont think I would want it to be a permanent replacement. I do think that it would interupt
some teaching and learning activity. I also think there will be a significant implication for teaching style.
Really importantly and potentially one of the most exciting implications of using these calculators is likely to be the increased emphasis on estimation as a skill. There are so many reasons to encourage this, but my favourite is because of the potential impact on understanding.
Specific activities
I think that these calculators could introduce a whole new level to activity design. Here are a few ideas that have popped in to mind in the first few days I have had this calculator....
Percentage error  I am really curious about the margin of error that the calculator is accepting in different contexts. My colleague tried log120 and was denied with an estimation of 2.1 Quite demanding I think, but there is a lot of potential to investgiate different types of operation and the percentage error allowed.
Least guesses  I like the idea of some activity where students have to try and estimate difficult operations in as few guesses as possible.
Trigonometry  I had fun estimating some trig ratios. I found myself thinking about the ratio between different sides of a traingle and how it would change as the angle increased. What a great way to encourage students to think about what trig ratios actually mean.
Again  this is just a start of lots of ideas that are bound to come from playing with these calculators.
Thanks Qama for these  a really exciting development.