Can They Subtract?
Faced with a reluctant or struggling math student, the first step is always just to get them to do the work. Then, with time, using more creative teaching techniques, introduce your student to alternate methods that he or she can use in order to subtract.
I had a grade three student come with a homework page of subtraction. He just sat and stared at it. I told him to look at the lower number and count up to the top number to get the answer. Though slow, he was able to do the whole sheet. He not only could now subtract but the fear factor was removed.
If they can't subtract at all:
- Begin by simply having them count up – you may need to suggest that they count up using their fingers or counters.
This will be very slow initially but it will get them over the 'I can't do it' hump and allow them to have a tool they can use to tackle early subtraction assignments. - Introduce them to tricks like 'magic nine'. (magic nine worksheet)
To subtract nine from basic two-digit minus facts (involving numbers 11 through 19), the student just adds the top numbers together.
eg. 14 - 9 = (1+4) or 5 - Use the math ladder method. (math ladder worksheet)
Take the bottom number and subtract it from ten, then add it to the ones digit of the top number.
eg., 16 - 7 = (10-7=3) + 6 = 9
I use this as the 'bait' to get the students to work with me. I tell them I can teach them how to subtract all the nines in just one minute. Everyone is a winner – I have willing students and relieved parents – The students can put their hands up in class to answer the difficult minus nine question so they feel successful.
Struggling students often need an alternative strategy to move past a learning barrier. This tool is great – especially for older students who are still struggling with their basic subtraction facts but already know what 'ten minus a number' is. Using the math ladder technique, they find that they can answer all the subtraction questions very quickly. Speed is essential when doing basic math facts because if it is taking more than five seconds to come up with the answer, what will happen when they have to do complex math calculation?
The struggling math learner will ultimately master regular subtraction, however giving them an alternative method, such as magic nines or math ladders, allows them the freedom to chose between techniques and, most importantly, they are not prevented from progressing with their classmates, as the teacher moves on to other math facts.
See the Math Skills section for more help.
See our Teaching Resources for Math Subtraction for worksheets, lesson plans, etc.
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