Activity 3 has students use a number strip and an abacus to count by 10s and to show numbers 10, 20, 30, …, 100. The activity asks specific subtraction questions such as "Which number is 10 less than 40?" and "If you had 50 pennies and lost 10 of them, how many would you have?" Activity 2 asks students to give change from a ten-dollar bill using one-dollar bills and to record or draw purchases on a whiteboard.

Students use concrete models (abacus, counters, laminated number line, and egg carton) to create and solve subtraction sentences, including tasks where they add 10 to numbers before subtracting (Option 1 and Option 2). The worksheet and activities include explicit subtraction problems such as 20 − 10 and several subtractions within the 10–20 range that students solve using the abacus, counters, or number line. Students are prompted to begin subtraction with the larger number and to check work with counters, modeling subtraction physically.

Students manipulate base-10 blocks and an abacus to show numbers (Activity 1) and trade 10 ones for a ten and 10 tens for a hundred flat, demonstrating place value and using concrete models. Students count and group objects by tens in Activity 3, place objects into 10 baggies/plates, and are asked questions such as "How many more do you need to get to 100?" and to count by tens to verify totals. Students complete a number grid from 91 to 100 and use the abacus to represent those numbers, reinforcing tens-and-ones structure through drawings and models.

Students use the abacus, ten rods, base-10 blocks, and a laminated number bond to find what tens must be added to a given multiple of ten to make 100 (e.g., 30 + 70 = 100, 40 + 60 = 100). Students write and read number sentences such as 3 tens + 7 tens = 10 tens and 30+70=100, and they physically split 10 ten rods into two groups to show pairs of tens that sum to 100. Activities ask students to show numbers in tens (e.g., 5 ten rods = 50) and then add tens to reach 100 using concrete models.

Students practice adding and subtracting 10 using concrete models: they add a ten-rod to unit blocks and move beads on an abacus to show +10 and -10. Students use number grids to count up and back by tens, fill in missing multiples of 10 (e.g., 10, __, 30, __, 50) and circle 10 more/10 less for given numbers. Activities ask students to count back by 10 from numbers and to color or name numbers that are 10 more or 10 less (e.g., 55 → 65 and 45; 100 → 110 and 90).

Students use base-10 blocks and an abacus to model subtraction problems such as 40-20, 60-30, and 80-20 (Activity 3) and are prompted to count remaining tens after removing ten-rods or moving beads. The student activity pages ask students to draw base-10 blocks for addition and subtraction of multiples of ten and to match subtraction number sentences (e.g., 60 - 30, 90 - 50) to their differences. Teachers prompt students to write number sentences on the whiteboard and to explain actions (e.g., "Why did I remove 2 ten rods?") and to note that subtraction is the opposite of addition, linking concrete strategy to written methods.

Students solve and match number sentences involving multiples of ten (for example, 90-40, 60-20, 50-30) in the "Multiples of 10 Concentration" activity. They are prompted to use concrete models (base-10 blocks or an abacus) and the teacher models place-value reasoning (for example, 5 tens − 2 tens = 3 tens) and links tens to ones. Activity 1 and the "10 More/10 Less" practice have students change the tens digit when adding or subtracting ten, reinforcing place-value strategies.

The Today's Number routine asks students to compute "10 more" and "10 less" for given numbers (examples: 26 -> 36 and 16; 57 -> 67 and 47). Students are instructed to represent numbers with base-10 blocks and to record numbers in a Hundreds/Tens/Ones chart. The lesson repeatedly has students show numbers with tens and ones and to draw base-10 blocks as concrete models.

Students represent numbers using ten rods and unit blocks (e.g., "4 ten rods and 8 unit blocks" for 48 and "7 ten rods and 9 unit blocks" for 79). Students practice finding "10 more" and "10 less" for those numbers (79 -> 69 and 79 -> 89; 48 -> 38 and 48 -> 58). The scavenger hunt and measurement activities explicitly use base-10 ten rods as concrete units that students handle and count.

Students represent the number 66 with six ten rods and six unit blocks and are prompted to find 10 more (76) and 10 less (56). Students are sometimes asked to name numbers that are 10 more and 10 less than a given two-digit number. The activities use ten-rods/units to show place value for a two-digit number.

Students count and group unit blocks into tens and ones and name numbers (e.g., show 3 ten rods and 4 unit blocks as 34). Students use base-10 blocks and the abacus to find sums and differences and to answer questions about '10 more' and '10 less' by adding or removing ten rods. Students write numbers in tens-and-ones form and in expanded form (e.g., 5 tens + 6 ones and 50 + 6 = 56), linking concrete representations to written number sentences.

Students use the abacus and base-10 blocks to model and compute differences (Activity 4: 60-40) and are prompted to think of subtraction in tens (e.g., "6 tens take away 4 tens"). Students draw number cards (10–100) and write subtraction number sentences on the whiteboard, then find the difference using concrete materials. Students practice additional subtracting-tens problems via an online activity and are encouraged to move toward mental strategies when ready.

The introduction prompts students to use base-10 blocks and an abacus to find differences (e.g., moving beads in groups of ten and starting with the larger number). Activity 1 has students toss coins to get two multiples of ten, write both an addition and a subtraction sentence, and find the difference while being reminded to think in tens (e.g., 3 tens vs. 6 tens). Activity 2 and the worksheet provide multiple subtraction problems with two-digit multiples of ten (for example, 60 - 50, 80 - 20, 90 - 50, 40 - 20) and instruct students to determine whether to add or subtract and to think of multiples of ten as numbers of tens.

Students use concrete models (base-10 blocks and an abacus) to compose tens and to add ones to reach the next multiple of ten (e.g., 35 + 5 = 40; 24 + 6 = 30; 46 + 4 = 50). Students practice finding missing addends on the "What's Missing?" sheet and match addition problems to sums on the matching sheet, and they are asked to identify the next multiple of 10 and what to add to reach it during the Wrap-Up. The materials prompt students to think about place value (exchanging ten ones for a ten rod) and the relationship between addition and finding a missing addend.

Students are asked to draw number cards 10–90 and answer questions including "What number is 10 less?" and "What number is 10 more?" The Skills list explicitly includes "Given a two-digit number, mentally find 10 more or 10 less than the number." Students use place-value materials (laminated mat, base-10 blocks, abacus) to show numbers and talk about tens and ones when finding next/previous multiples of ten.