Students use a number line to add pairs of numbers (e.g., directions and sheet with problems like 6 + 10 and 8 + 12) and practice counting forward by jumps to find sums. Students use the abacus including the place-value side (1000,100,10,1) to add numbers and regroup beads to make tens (for example modelling 8 + 7 = 15 and showing 10 + 5). Students explore and generate turn-around facts by rolling dice and writing both a + b and b + a, demonstrating the commutative property of addition. Activity 5 asks students to record addition number sentences using one- and two-digit numbers found around the house.

Students practice adding two-digit numbers in multiple places: they solve Two-Digit Addition problems (e.g., 28+17, 36+29) and write vertical addition sentences. Students use place-value tools and strategies to add: they model sums with base-10 blocks and an abacus, compose tens (circle 10 ones to regroup), count up by tens mentally, and play Race to 100 using ones-to-tens exchanges. The lesson also presents and practices properties and strategies such as the commutative property, doubles, doubles-plus-one, and making tens.

Students practice place-value strategies for addition by using a take-and-give method to make tens (e.g., turning 39+6 into 40+5, and writing 59+3 as 60+2). Students use mental math with an abacus to add 9s and 8s to larger numbers and are asked to explain their steps and use the commutative property (turn-around facts) such as 4+9 = 9+4. Students complete worksheets with problems like 39+3, 48+6, 17+8 and check answers with manipulatives.

Students are given an explicit two-digit addition problem (35 + 14) and are allowed to use materials of their choice to find the answer. Students build and count tens and ones with base-10 blocks, place hundreds/tens/ones on a laminated place value mat, and count and record hundreds, tens, and ones in multiple activities (Activity 4 and the Student Activity Page). The Skills section explicitly lists "Add and subtract two-digit numbers."

Students pick two number cards (1–50), write two-digit addition sentences in two orders (e.g., 34+15 and 15+34), and find answers using materials or strategies of their choosing. The skills list explicitly includes "Add and subtract two-digit numbers." Students use base-ten blocks and place-value cards to represent numbers and identify hundreds, tens, and ones values.

Students practice adding two-digit numbers in multiple activities: Box 7 (Dicey Two-Digit Addition and Subtraction) has students roll four dice to form two two-digit numbers and create addition sentences, and Box 8 (Close Call: Two-Digit Addition) has students choose four cards to form two two-digit numbers and write their sums on scorecards. The materials encourage use of manipulatives (base-10 blocks, abacus) and modeling, and the Close Call activity explicitly models thinking aloud about adding in the ones place and carrying to the tens place.

The Wrapping Up section lists vertical number sentences including two two-digit addition problems (34 + 25 and 56 + 18) and instructs the child to "use the strategies and methods of her choosing" to find the sums. The Introduction and Skills sections prompt students to identify hundreds, tens, and ones on number grids and state that students should "Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones," which addresses place-value understanding.

Students are given two two-digit addition problems (29 + 55 and 36 + 45) written vertically for them to solve, and they are told to use strategies and materials of their choosing to find the sums. Students practice place value concepts by completing number grids up to 600, counting by 10s and 100s, and identifying how the hundreds, tens, and ones digits change. The activities include reading and writing numbers to 1000 and discussing which digit changes when counting by tens or hundreds.

Students practice adding multiple two-digit numbers using place-value tools and strategies throughout the lesson: Activity 3 has students add three two-digit numbers using base-10 blocks, expanded form, and regrouping on paper. Activity 4 explicitly has students add three and then four two-digit numbers by creating numbers with dice and using base-10 blocks, abacus, and reordering (making tens) to simplify sums. The abacus and "Adding Over 100" activities require composing tens into hundreds and lining ones and tens in vertical addition, showing place-value based regrouping and use of the commutative/turn-around property.

In the Introduction, students are instructed to use a number generator set to create an addition sentence with three addends and an addition sentence with four addends (numbers between 1 and 50) and to find the sums using their preferred approach. The Skills section states students will "fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction." Activity 4 has students use addition (fact families) to check subtraction work, which requires forming and computing two-number addition sentences.

Students draw two number cards (1–99), create an addition sentence with the two numbers, write it on grid paper, and find the sum; this process is repeated multiple times. Students are encouraged to work without manipulatives but are allowed to use base-ten blocks, a laminated place value mat, or an abacus to compute sums. The instructions remind students that they may need to regroup as they work, indicating attention to place-value regrouping in addition.

Students solve a two-digit addition problem (35 + 47) on paper and are guided to use regrouping and expanded form to find the sum, showing explicit use of place-value strategies. Students use base-10 blocks and the abacus to represent numbers and check sums (for example, modeling 572 + 300 and 657 + 274), reinforcing addition by hundreds, tens, and ones. Students are asked to add vertically beginning with the ones place and to compose tens and carry, demonstrating procedural place-value methods for addition.

Students draw place-value cards to build three-digit numbers and answer questions about tens and hundreds (e.g., "What is 10 more? 100 less?"). Students play the Close Call Addition game where they choose cards to create two three-digit numbers to add and are encouraged to use base-10 blocks, an abacus, place-value mats, and to hear think-alouds about starting in the ones place and carrying to the tens. Students complete the "I Can Add and Subtract Three-Digit Numbers!" worksheet with multiple three-digit addition problems and may use manipulatives or mental math to find sums.

Students read distances on the map, decide whether to add or subtract, write number sentences, and compute sums or differences for travel questions. The materials list and directions let students use an abacus, base-10 blocks, and a laminated place-value mat while solving and prompt them to check regrouping/borrowing. The answer key includes problems that require adding multiple addends (for example, 188 + 147 + 174 and 184 + 100 + 174), showing practice with multi-addend addition.

Students complete an "Addition and Subtraction Practice" sheet that includes two-digit addition problems (for example 67 + 75) and are encouraged to use mental math and manipulatives. The instructions tell students to line up place values correctly and remind them they may need to compose 10/regroup, which directs them to use place-value-based regrouping when adding.

In Activity 2 (Swimming!), students answer questions that require combining and comparing lap times, including "How long altogether did Karen, Greg, and Ally swim laps?" and "How much longer did Emmy swim laps than Scott?". The lap times table includes two-digit durations (e.g., 20, 35, 40 minutes). The directions allow students to use concrete place-value tools (abacus, base-10 blocks) as they answer the questions.

Students cut out activity boxes labeled with durations (1 hour, 30 minutes, 15 minutes) and place one to four activities into hourly blocks (Step 3 and Step 4). The materials prompt students to combine two 30-minute activities to make an hour and to combine four 15-minute activities to make an hour, and ask students to check that the activities in each hour block "add up to an hour" and to "prove this." The Day's Activities sheets present many activities with times in hour, half-hour, or quarter-hour increments that students must add together to create a daily schedule.

Students practice counting by tens and fives to 200 and are asked what happens to the tens and ones digits when counting by 10s, supporting place-value thinking. In Activity 2 students count groups of coins by counting dimes, then nickels, then pennies and write the amounts (for example, counting 3 dimes, 2 nickels, and 4 pennies to get 44¢), which requires adding values by place (tens and ones). In Activity 4 and the Wrapping Up students compose two-digit cent amounts (e.g., 62¢, 59¢, 78¢) by combining dimes (tens) and pennies/nickels (ones), and they exchange coins (5 pennies ↔ 1 nickel, 2 nickels ↔ 1 dime) to regroup by tens.

Students use base-10 blocks and an abacus to represent and find values for 1–4 quarters (25¢, 50¢, 75¢, 100¢). Students count coin collections by tens and ones (e.g., counting dimes by 10, exchanging pennies to nickels and nickels to dimes) and match groups of coins to two-digit cent amounts such as 38¢, 55¢, 46¢, 82¢, 79¢, and 64¢. Students play an exchange game that requires grouping pennies into nickels and dimes and counting totals when reaching 25¢.

Students count and combine values of coins in multiple activities: they make target amounts for cups (e.g., 99¢, 73¢, 84¢) by selecting and adding quarters, dimes, nickels, and pennies, and they compute the value of pictured coin groups on the "Matching Amounts" sheets. In the exchange game students collect pennies, add those amounts, and exchange to larger coins as they accumulate toward 100 cents. The wrapping up problems ask students to show specific totals (76¢, 87¢, 92¢, 89¢) using as few coins as possible, requiring them to add coin values to reach those two-digit amounts.

Students add coin values to find totals in multiple activities: they calculate which coin path equals 87¢, 68¢, 54¢, and 71¢ by summing coin denominations, and they match people to sticker prices (e.g., 78¢, 84¢, 98¢) by counting and adding coins. In "What's in My Wallet?" students combine up to four coins (for example, two quarters and two nickels to make 60¢) and draw coin combinations to reach given two-digit cent totals. The dice starter has students generate four two-digit numbers (from dice rolls) and represent each amount with coins.

Students count and combine coins to make dollar amounts (e.g., gluing coins to show 1 dollar, grouping 4 quarters, 10 dimes, 20 nickels). Students count dimes by tens and nickels by fives to verify totals and represent amounts such as $1.25 and $1.45 using a dollar bill plus coins. Students match pictured collections of a bill and coins to written dollar amounts (e.g., connect $1.30, $1.55, $1.24 etc. to corresponding coin groupings).

Students are asked to "count cent and dollar amounts" and to "solve word problems involving dollar bills, quarters, dimes, nickels, and pennies," which requires combining money amounts. The "Project Coins and Bills" page lists multiple bills and coins (several $1 and $5 bills and many coins) that students can use to make and total amounts. Activities include matching collections of coins with their amounts and creating games that show money amounts, and students must write answers on index cards and copy amounts onto the cereal box.

Students practice adding and subtracting using place value when they count by tens and hundreds and when they solve problems like 456+30 and 456+300, explaining which place changes. Students complete problems that require adding two-digit to two-digit or two-digit to three-digit numbers on the worksheet (e.g., 39+50, 45+20) and work with vertical addition on grid paper where they are reminded about composing tens and carrying. Students also use place-value alignment and are asked to explain the role of zero and which digit positions change during operations.