Adding and subtracting within 20
Students solve story problems by adding and subtracting small numbers. They learn tricks like counting on from the bigger number and making a ten to get the answer faster.
This is the year math stretches past ten. Students add and subtract within 20 until the easy facts come quickly, and they start seeing numbers up to 100 as bundles of tens and leftover ones. They measure objects with rulers, tell time on a clock to the hour and half-hour, and split shapes into halves and fourths. By spring, students can solve a word problem like 8 + ? = 14 and explain how they got there.
Students solve story problems by adding and subtracting small numbers. They learn tricks like counting on from the bigger number and making a ten to get the answer faster.
Students count, read, and write numbers all the way to 120, starting from any number. They begin to see that a two-digit number is made of tens and ones, so 34 means three tens and four ones.
Students add two-digit numbers using drawings and place value, sometimes trading ten ones for a new ten. They also find 10 more or 10 less in their head and subtract tens like 70 minus 40.
Students line objects up to compare lengths and measure with paper clips or cubes. They tell time to the hour and half hour on clocks, and sort information into simple charts they can read.
Students name shapes by what makes them that shape, like the number of sides, not the color or size. They put shapes together to make new ones and split circles and rectangles into halves and fourths.
| Standard | Definition | Code |
|---|---|---|
| Distinguish between defining attributes | Students learn which features actually make a shape what it is. A triangle is always three-sided and closed, but its color or size don't define it. Students sort shapes by their real rules, then draw or build shapes that follow those rules. | CA-1.G.1 |
| Compose two-dimensional shapes | Students fit basic shapes together, like triangles and squares, to build a bigger shape. Then they use that new shape as a building block to make something bigger still. | CA-1.G.2 |
| Partition circles and rectangles into two and four equal shares, describe the… | Students cut circles and rectangles into two or four equal pieces and name each piece a half, a fourth, or a quarter. They also notice that cutting a shape into more pieces makes each piece smaller. | CA-1.G.3 |
| Use appropriate tools strategically | Students identify shapes that can be split into two equal halves, like a square cut down the middle. They learn that equal parts are the same size. | CA-1.G.5 |
| Attend to precision. Measurement and Data | Students sort and measure objects using the same unit throughout, such as lining up paper clips end to end without gaps or overlaps. Getting this right is what makes the measurement mean something. | CA-1.G.6 |
| Look for and make use of structure | Students sort and describe shapes by their sides and corners, noticing what makes a triangle different from a rectangle. They look for patterns in how shapes are put together. | CA-1.G.7 |
| Standard | Definition | Code |
|---|---|---|
| Order three objects by length | Students line up three objects from shortest to longest, then figure out which of two objects is longer by comparing each one to a third object, like a piece of string. | CA-1.MD.1 |
| Express the length of an object as a whole number of length units, by laying… | Students measure how long something is by lining up smaller objects, like paper clips or cubes, from one end to the other. The total number of those smaller objects is the length. | CA-1.MD.2 |
| Tell and write time in hours and half-hours using analog and digital clocks | Students read a clock and write times like 3:00 or 3:30, for both analog and digital clocks. They also collect simple information, such as counting how many students prefer dogs or cats, and read a chart showing the results. | CA-1.MD.3 |
| Organize, represent, and interpret data with up to three categories | Students sort objects or answers into groups, count how many are in each group, and compare the groups. For example, they might tally favorite colors and figure out which got the most votes and by how much. | CA-1.MD.4 |
| Standard | Definition | Code |
|---|---|---|
| Count to 120, starting at any number less than 120 | Students count, read, and write numbers up to 120, starting from any number, not just 1. They also show how many objects are in a group by writing the matching number. | CA-1.NBT.1 |
| Understand that the two digits of a two-digit number represent amounts of tens… | Students learn that every two-digit number is made of tens and leftover ones. The number 37, for example, is three tens and seven ones. | CA-1.NBT.2 |
| Students need not use formal terms for these properties | Students compare two numbers under 100 and say which is greater, which is less, or whether they match. They use what they know about tens and ones to explain why. | CA-1.NBT.3 |
| Add within 100, including adding a two-digit number and a one-digit number | Students add numbers up to 100 by grouping tens and ones separately. They use blocks, drawings, or written steps to show their thinking and explain why their method works. | CA-1.NBT.4 |
| Given a two-digit number, mentally find 10 more or 10 less than the number… | Students pick a two-digit number and figure out what's 10 more or 10 less in their head, no counting allowed. Then they explain how they knew. | CA-1.NBT.5 |
| Subtract multiples of 10 in the range 10–90 from multiples of 10 in the range… | Students subtract round numbers by tens, like 70 minus 40, using blocks or drawings to show their thinking. They connect what they did with the objects to what they write on paper. | CA-1.NBT.6 |
| Standard | Definition | Code |
|---|---|---|
| Use addition and subtraction within 20 to solve word problems involving… | Word problems ask students to add or subtract numbers up to 20. Students figure out what's missing, whether it's the starting amount, the change, or the result. | CA-1.OA.1 |
| Solve word problems that call for addition of three whole numbers whose sum is… | Students add three numbers together to solve a simple story problem, keeping the total at 20 or under. They might use drawings, counters, or a number sentence to find the missing piece. | CA-1.OA.2 |
| Apply properties of operations as strategies to add and subtract.3 Examples | Students learn that flipping the order of two numbers still gives the same sum, and that regrouping numbers in an addition problem can make it easier to solve. | CA-1.OA.3 |
| Understand subtraction as an unknown-addend problem | Subtraction is the flip side of addition. To solve 10 minus 8, students think "what do I add to 8 to get 10?" instead of counting backward. | CA-1.OA.4 |
| Relate counting to addition and subtraction | Counting up or back on a number line is one way to add or subtract. Students practice seeing that counting forward 3 from 7 is the same as adding 3. | CA-1.OA.5 |
| Add and subtract within 20, demonstrating fluency for addition and subtraction… | Students add and subtract numbers up to 20, and do it quickly and reliably up to 10. They use shortcuts like breaking numbers apart or using what they know about tens to find the answer without counting every finger. | CA-1.OA.6 |
| Understand the meaning of the equal sign | Students learn that the equal sign means "both sides are the same amount," then decide whether a number sentence like 5 + 2 = 2 + 5 is true or false. | CA-1.OA.7 |
| Determine the unknown whole number in an addition or subtraction equation… | Students find the missing number in simple addition and subtraction equations, like figuring out what goes in the blank to make 8 + ? = 11 true. | CA-1.OA.8 |
| Explain why addition and subtraction strategies work, using place value and the… | Students explain *why* a math trick works, not just that it does. They use what they know about tens and ones to show why adding or subtracting in a certain order still gets the same answer. | CA-1.OA.9 |
The grade 3 math test in the CAASPP suite. Adaptive computer-based questions plus a performance task covering the Common Core grade 3 math standards.
The state test for students with the most significant cognitive disabilities. Replaces Smarter Balanced math in grades 3-8 and 11 for the small group of students whose IEP teams qualify them.
Students should add and subtract within 20, know addition and subtraction within 10 by heart, count to 120, and understand that a two-digit number is made of tens and ones. They should also tell time to the hour and half hour, measure with a ruler, and name basic shapes by their parts.
Play quick number games while cooking or driving. Ask things like "what is 8 plus 6?" or "if we have 13 grapes and eat 5, how many are left?" Count coins, read the clock together, and look for shapes around the house.
Students answer facts like 7 plus 3 or 9 minus 4 within a few seconds, without counting on fingers every time. They use tricks like making ten or doubles. Speed is not the goal. Confident, accurate answers are.
Start with counting on and number bonds within 10, then build fact strategies like making ten and using doubles. Move into word problems with unknowns in every position, then into adding two-digit numbers using tens and ones. Save mental 10 more and 10 less for once place value is solid.
Not at this age. Fingers are a normal tool while students build number sense. Over time, gently nudge toward strategies like making ten or remembering doubles. If finger counting is still the only strategy by spring, mention it to the teacher.
Place value with teen numbers trips up a lot of students, since "thirteen" sounds like three and not ten and three. The equal sign also causes trouble once equations look like 8 plus blank equals 11. Plan extra time for both.
Fractions show up as halves and fourths of circles and rectangles, with words like "half of" and "a quarter of." Cut sandwiches, pizzas, and paper into equal parts at home and talk about how four small pieces still make one whole.
By spring, students should solve word problems within 20 with unknowns in any spot, add a two-digit number and a one-digit number using tens and ones, tell time to the half hour, and compare lengths using a smaller object as a ruler. If those feel shaky, spend extra time there before year end.