In this unit, the students will develop strategies for adding and subtracting whole numbers by using addition charts, mental math, estimation, base ten blocks, place value mats, as well as the standard algorithms using pencil and paper. Here are the expectations for this unit. - Recall basic addition and subtraction facts - Identify the relationship between addition and subtraction - Add and subtract 2-digit and 3-digit numbers - Describe patterns in addition and subtraction - learn strategies for additional and subtraction - Solve and explain addition and subtraction problems - Use mental math to add and subtract - Estimate sums and differences The ability to use a variety of strategies to add and subtract leads to the development of a strong sense of number. Numbers are all around us and the skills taught in this unit are essential for daily living. To help your son/daughter completing daily review of number facts goes a long way! Practising the concepts of "borrowing" (when subtracting) and "carrying over" (when adding) will help him/her to remember these strategies. Students should become aware of Related Facts. These are 3 numbers that can be used to make 2 addition sentences and 2 subtraction sentences. Example - 4, 9, 13. 4+9=13, 9+4=13, 13-4=9, 13-9=4 It will also be helpful for the students to practice and memorize their doubles facts. Example - 5+5=10, 7+7=14 |
Doubles and Near doubles:
A Double is when you take the same number and add it together. example: 2+2 A Near Double is either one higher or one lower than a double. example: 2+3 or 1+2 Patterns that students have noticed is that the sum (answer) of a double is always an even number. where the sum (answer) of a near double is always an odd number. Students stretch their thinking when when they are given a sum (answer) and must find the doubles or near doubles to make it true. Example: The sum is 36... -I know this is a double because it is an even sum. -I ask myself what is 1/2 of 36? - the answer is 18 so...18+18= 36 The sum is 37... - I know this is a near double because it is an odd sum. - Because I know that 18+18=36 and 37 is one number bigger than 36 I add 1 to one side of the equation. -18+19=37 |
Problem SolvingWe have been working on our problem solving skills in class, not only is this a valuable skill as part of the grade 3 curriculum but it is something that they will see during EQAO.
We are practicing answering problem solving questions using this think box (each section of the box is labeled as Pictures, Numbers, Words, Explain). The most important part is for the student to be able to explain how they came to their answer this involves a detailed description of the steps that they took to get the answer. |
Addition with regroupingFirst: count the ones
Ask: Do you you have any 10's in the one place? If you do you need to move the 10's over to the 10's place. (see picture for an example. Next count the 10's Ask: Do you have any 100's in the 10 place? If you do you need to move the 100's over to the 100's place Practice Questions: 324 + 295= 22 + 36= 98 + 22= 749 + 123= 687 + 53= 25 + 25= 874 + 118= |