1. Learning facts
Learners with dyslexia often find it difficult to learn basic number facts ?off by heart?. Knowing number bonds to 10 are essential (that is, knowing off by heart all the combinations of adding two single digits; 2 + 8, 4 + 7 etc) and no matter how long it takes, learning these facts is even more important than later learning tables. Visual patterns can help with this, as will constant use of counters or coins to show similarities between adding eg 5 + 5 and 5 + 6. It is a good idea to make use of the facts the child does know to help them know a new fact.
Many people learn these facts as ?verbal associations? or short phrases such as 8 plus 6 equals 14; this is even more true about learning tables. It is of little use to learn the two times table by saying 2, 4, 6, 8 etc. The association between the two numbers and the answer needs to be verbally ?fixed? ie ?three times two is six?, or shorter, ?three twos are six?. However these methods are difficult for dyslexia learners to process and access is often very slow. They often rely on a few known facts and use counting on to work out the next. A test such as the mental arithmetic test in the Year 6 SATs where a very limited amount of time is available can be very stressful.
It is a good idea to encourage jottings to help with mental calculations. This is not the same as a written method but a way of jotting down a part answer which might otherwise be difficult to hold ?in your head?.
2. Step by step
In the later years of the primary schools many questions involve using a sequence of steps to reach the correct answer. This is especially true of written methods of addition, subtraction, multiplication and division. Children with poor working memories will find it difficult to execute these steps in the correct order. Combine this with a shaky knowledge of number bonds and it is easy to see why many dyslexic learners lose all confidence and feel overwhelmed.
To become confident with multi-step strategies much time needs to be spent with using just a two step approach. For example, taking 9 by subtracting 10 and adding 1. URbrainy has a wealth of resources using these kinds of methods.
3. Written methods.
When working mentally it is quite usual to work with the most significant figure first eg adding 34 and 45, by adding 30 and 40 first and then adding the units.. Written methods usually favour starting with the least significant. This can lead to problems.
Another very common problem is that a mental calculation may be correctly worked out but the digits written down in reverse order, so the answer will be incorrect. It is very important that children show their working out, as incorrect answers can be studied to see exactly where the error is occurring.
Calculators in Primary Schools came into fashion and then seemed to go out of fashion again, which is a pity as they are capable of showing much that is fascinating about number, and no-one is suggesting that they should replace fast mental methods of calculating or pencil and paper methods. Rather, they should be used at some stage in a question and not as a total solution.
Calculators may well help dyslexic learners access more mathematics but they can be a problem in themselves, as difficulties arise between reading a number on a page and inputting it correctly on the calculator. Hence, there is a real need for all children to develop some quick methods of making sensible estimates to answers before using a calculator; in this way they can recognise calculator results which are way off, for example, by missing a decimal point.