This week we also tested on Topic 3- Subtraction. Pretest scores showed students had limited knowledge on basic subtraction skills (regrouping/borrowing & estimating). We spent the week learning how to regroup and other strategies to help them subtract. They learned basic skills, such as, adding up to find the answer, counting up by 10's and then adding on ones, using models (counters/base 10 blocks), and then simple regrouping to find the answer. Adding up to find the answer means if you have a problem, such as, 27-18. Start at 18 and add up to get to 27. Counting by 10's means that if you have a problem, such as, 79 - 49, you can count up by 10's from 49 to 79 to find the answer. If the problem is 79 - 45, you count up to the 10's that is closest to 45 and then add on the four ones (Start at 45 and add 10's = 55, 65, 75, and then add the 4 ones. That took 3 tens = 30 and 4 ones = 4, so the answer to 79-45=34).
One area of concern for many students is that they did not grasp basic regrouping (borrowing) skills in 1st and 2nd grade. I noticed that several students did not know what to do when the top digit in the ones place was less than the bottom digit in the ones place:
After looking at student's post test scores on Pearson, we are going to have to work on regrouping strategies more. Like I said earlier, this is a skill that should have entered 3rd grade with, but many have not. If you want to know if your child knows regrouping skills, give them a problem, such as the one above, and see if they can regroup, without your help. Look to see if they know what to do when that top digit is smaller than the bottom digit. Do they know what to do when they borrow from the 10's place value?
Have a great, long weekend!