The Complementary Abacus
Previously, when did you typically introduce a calculator to your students? What might you do differently now?
Create an addition and subtraction problem for the purpose of teaching the compliments of ten. Be sure to include at least five single digits.
Write a script describing the steps of adding nine to six.
I usually introduce the calculator in 5-6 grade in preparation for when they will be able to use it on state testing, unless student need dictates otherwise.
6+9+3-7-5
Set 9
Set 10
Clear 6 complementary number; 4
Answer: 15
Hi Lynda!
You problem is spot on for practicing addition and subtraction using complements of 10. Your instructions are short and sweet but I bet students would like it that way.
I typically introduce a calculator around fifth grade, sometimes before if their class is using them, then I would introduce before. It really is dependent on the student and what is happening in their classroom.
6+5+3-2
Set 6
add 5- the pair’s equivalent is 5;
move over to tens place and set 10
add 3 in the ones
subtract 2
answer 12
Hi Melissa!
Your problem does have an addition complement of 10. Nice work. I see you explained your own problem in #3 (sort of). In your instructions for your own problem you do not indicate removing the 5 bead from the ones column after you set the one bead in the ten’s column.
Do you want to try writing a script describing the steps of adding nine to six?
I am not a teacher yet but I feel like a calculator wasn’t introduced to me until middle school or late elementary.
7 + 3 - 5 + 6 - 2
Start with 7
Add 3: 7+3=10
7+3=10 (This demonstrates the complement of 7 and 3 making 10)
Subtract 5: 10−5=5
Add 6: 5+6=11
Subtract 2: 11−2=9
Final result: 9
Hi nieberding.28, your problem is actually quite complex with multiple complementary number movements. At this time you and your student have only learned the complements of 10. I suggest 7 + 3 + 5 + 3 - 2 so your student has more success.
Hi appleton.thea, would you still wait until sixth grade to introduce the abacus?
Your problem is a great introduction to the complements of 10 for your student.
Ooops! That was a mis-type!
I start showing them a basic abacus in preschool for counting. We work on abacus a lot more in elementary, and some students choose to use it in class. Some students fight it. I introduced a talking calculator to my students at a young age, as a way to check calculations done on their braille writer or abacus. However, I didn’t provide them a TALKING CALCULATOR to use at-will in class until the same time as their peers - about 5th or 6th grade. I don’t think I would change when I teach these skills.
I’m not a teacher, but I believe I started using calculators the beginning of 6th grade.
6+1+1+9-1
Write a script describing the steps of adding nine to six.
Set up the number 6 (5 bead & 1 bead)
Add 1 extra bead
Add another 1 bead
To add the 9, we will have to look at the tens column and push up 1 ten bead. We must remember the complement number of 10 and 9, which is 1. We will push down 1 bead from the ones column.
Lastly, we will remove 1 bead.
We are left with 10 and 6, and the total would be 16.
Hi mohamoud.25!
Your problem is a great starting problem to introduce the complementary addition of 9 and 1.
The first two steps in your directions for adding nine and six are unusual. I am not sure why you are doing these parts: ‘add 1 extra bead; add another 1 bead’
In addition, your last step, ‘lastly, we will remove 1 bead’ seems unnecessary. With all of these unneeded steps, you have come to the wrong answer of 16. The answer should be 15.
The only directions you need are:
Set up the number 6 (5 bead & 1 bead)
To add the 9, we will have to look at the tens column and push up 1 ten bead. We must remember the complement number of 10 and 9, which is 1. We will push down 1 bead from the ones column.
The Complementary Abacus
Previously, when did you typically introduce a calculator to your students? What might you do differently now?
Create an addition and subtraction problem for the purpose of teaching the compliments of ten. Be sure to include at least five single digits.
Write a script describing the steps of adding nine to six.
The only students who I have had on my caseload who needed VI-specific calculators were ones who were identified as needing IEP services later in their academic careers. By that point, they were in need of talking graphing calculators and talking large print calculators. I have been fortunate to witness and do some instruction with colleagues’ students with the Cranmer abacus, though. If I were to get a student who is young enough to begin working with either a beginner or Cranmer abacus and is emergent with math skills, then I would push for inclusion of this device as a tool to be used in the classroom, at home, and during testing. Depending on where the student is with math skills (PreK, kinder, elementary), I may pace the lesson differently, but I would still spend time orienting the student to the layout and function of the abacus. The student will need to build familiarity with the tool before being able to use it properly.
9 + 6 - 7 - 5 + 9 = 12
First, set the abacus to six by pulling down a 5 bead with the index finger and pushing up a 1 bead with the thumb. Check to make sure the Reckoning Bar has the 5 and 1 bead. Then add 9 - but wait! We can’t add 9 in the one’s column, so we move left to the 10’s column and add a 1 bead with a thumb. We learned that 9’s partner, or complement, is 1, so when we add 10, we take away a 1 bead. We are left with 1 bead in the 10’s column and the 5 bead in the one’s column. Our answer is 15.