Check students' place value understanding and rounding fluency before gameplay. Use conceptual questions alongside spatial tasks that surface both procedural knowledge and intuitive number sense.
Use place value to round to 10 & 100
- Use place value understanding to round whole numbers to the nearest 10 or 100. (3.NBT.A.1)
Before You Play
What does it mean to round to the nearest ten? To the nearest hundred? How are they different?
Listen for: Students who explain that rounding to tens looks at the ones digit ("if it's 5 or more, round up") while rounding to hundreds looks at the tens digit. Watch for confusion—students may think rounding 347 to 300 and to 350 are the same process.
If you need to build a number that rounds to 340, what numbers could work? What's the smallest? The largest?
Listen for: Students who identify the qualifying range: "335 to 344 all round to 340." Can they understand rounding as a range rather than a one-to-one procedure? Students who say "only 340 works" don't yet grasp that multiple numbers share the same rounding outcome.
Stand up and point to something about halfway between the front wall and back wall. Now point to something about 3/4 of the way back. How did you decide?
Watch for: Students who use spatial estimation and can explain their reasoning about relative position. This spatial thinking about "closer to" and "farther from" directly transfers to deciding whether 347 is closer to 340 or 350.
Listen for: Language about proximity: "It's closer to the back than the front" or "It's past the middle but not all the way." This shows they can think about position on a continuum—key for understanding rounding.
Hold your hands apart to show the distance from 300 to 400. Now show me where 347 would be between your hands.
Watch for: Students who position their hand closer to the 300 side (left hand) than the 400 side (right hand). This physical representation makes the concept of "closest hundred" concrete. Students who place their hand dead center or closer to 400 may not yet understand relative magnitude.
Setup Tip: Arrange materials so students can easily reach both the draw pile and their game mat. Give each player their mat before explaining rules so they can see the target sections (round to tens, round to hundreds) as you walk through gameplay. Make sure the two sections are visually distinct.
During Gameplay
Students make quick decisions about digit selection and number construction while managing limited cards and competitive pressure. Watch both their verbal reasoning and how they physically manipulate materials.
Setup & Target Recording
Look at your four targets. How do you know which ones require rounding to tens versus rounding to hundreds?
Listen for: Students who see the pattern: "If it ends in 0 for both tens and ones, it's a hundreds target like 500. If it ends in a non-zero tens digit like 340, it's a tens target." Do they understand the structural difference between target types?
Watch For: Whether students write targets in the correct sections with digits properly aligned in place value columns. Students who write 340 as "340" in a single cell may not be thinking about place value structure, while those who align digits in separate columns show stronger understanding.
Choosing Cards & Building Numbers
You have cards 2, 3, 5, 7, 8. What strategy will you use to decide which three to play and how to arrange them?
Listen for: Strategic reasoning like "I'll try to hit 530 by putting 5 in hundreds, 2 in tens, 7 in ones" or "I need to check which targets I can hit with these digits." Students who systematically evaluate options show stronger strategic thinking than those who guess randomly.
Before you commit, which digit in your arrangement determines whether it rounds up or down? Show me with your finger.
Watch for: Students who physically point to the deciding digit—the ones place for rounding to tens, the tens place for rounding to hundreds. This gesture confirms they know which place value controls the outcome.
Listen for: "For nearest ten, the ones digit decides. For nearest hundred, the tens digit decides." Students who point to the wrong digit don't yet understand which place value controls each type of rounding.
Facilitation Move: When students struggle with card selection, have them spread all five cards on the desk where they can see all options simultaneously. This visual organization helps them spot combinations they might miss when holding cards in hand. Ask: "Can you see any three cards that would make a number rounding to one of your targets?"
Verification & Scoring
You just built 347 to hit target 350. Walk me through how you know that's correct.
Listen for: Complete reasoning: "347 has a 7 in the ones place, which is 5 or more, so I round the tens place up from 4 to 5, giving me 350." Students who just say "because 7 rounds up" without connecting the ones digit to the tens place change may have procedural knowledge without conceptual understanding.
Point to your target on the game mat, then point to the number you built. What makes this number qualify for this target?
Watch for: Students who physically indicate both numbers and explain the connection. This simple pointing task helps them verify by seeing the constructed number and target together, making the relationship spatially concrete.
Listen for: Range reasoning: "My number 347 is between 345 and 354, which all round to 350." Do they understand that rounding creates equivalence classes where multiple numbers share the same outcome?
Slide your number card closer to one target and farther from another on your mat. Which target does your number physically sit closer to?
Watch for: Students who use physical proximity on their mat to verify rounding accuracy. Moving the card creates a spatial representation of numerical distance, helping them see which target their number naturally "belongs to."
Collaboration: In pairs, have partners verify each other's numbers before marking targets. Partner A builds a number, Partner B checks whether it truly rounds to the chosen target. This peer verification creates natural discussions about which digits matter.
Strategic Decisions
You can't hit any targets with your current cards. Should you discard and draw new ones, or try a harder target? How do you decide?
Listen for: Cost-benefit thinking: "I'll discard because none of my cards work" versus "I'll try the hard target because I'm close and discarding wastes a turn." Do they understand the trade-off between certainty and efficiency?
Watch For: Students who organize their cards systematically—grouping high digits, low digits, or arranging in order. This self-organization helps them see patterns and possibilities more clearly. Students who keep cards randomly jumbled often miss viable combinations.
After You Play
Help students articulate the strategies and patterns they discovered. Focus on consolidating understanding through reflection on decision-making and pattern recognition.
What strategy did you use? Did it change as you played more rounds?
Listen for: Strategic evolution like "At first I just took whatever cards I got, but then I realized I should target the easiest numbers first" or "I started paying more attention to which digits I needed." Can they articulate strategy development?
Which was harder: building numbers that round to specific tens (like 340) or to hundreds (like 300)? Why?
Listen for: Students who connect difficulty to range size: "340 was way harder because only 10 numbers work (335-344), but 300 has like 100 numbers (250-349)." Do they understand that qualifying ranges vary by place value and affect strategic difficulty?
Think about when you had to decide between two possible numbers. How did you choose which to build?
Listen for: Decision-making reasoning: "I could make 347 or 374, but 347 hit a target I hadn't finished yet" or "I chose the number that used my hardest digits so I'd have easier cards left." This shows strategic thinking beyond just applying rounding rules.
Gesture with your hands to show the range of numbers that round to 340. Now show the range for 300. What do you notice?
Watch for: Students who physically demonstrate different-sized ranges with their hands—a small span for 340 (just 10 numbers) versus a much wider span for 300 (100 numbers). This embodied representation makes the abstract concept of "qualifying range" tangible.
How is building numbers that round to a target different from just rounding a given number?
Listen for: Conceptual insights like "When you round, you just follow the rule, but when you build, you have to think about what numbers work" or "I learned that lots of different numbers can round to the same target." Do they understand rounding as a many-to-one relationship?
Extensions & Variations
Strategic Target Selection
Players choose their own four targets at the start (two tens, two hundreds). This adds a strategic planning phase where students must think about which targets offer the best winning chances given probability and range sizes.
Range Recording Challenge
After building each number, students write the complete qualifying range for that target (e.g., "335-344 rounds to 340"). This makes the range concept explicit and builds systematic thinking about rounding intervals.
Number Line Placement
Create a large number line from 0-1000 on the board marked in tens. As students build numbers, they physically place them on the line and verify they're in the qualifying range for their target. This makes rounding ranges spatially concrete.
Four-Digit Extension
Add a 0 card and extend to four-digit numbers with "round to nearest 1,000" targets. Students now manage an additional place value and must track which digit controls rounding when working with thousands.
Multiple Rounding Challenge
Each constructed number counts toward two targets simultaneously: one tens target and one hundreds target. For example, 347 rounds to both 350 (tens) and 300 (hundreds). This reveals that rounding outcome depends on chosen place value.
Physical Number Line Walk
Tape a floor number line from 300-400. After building a number, students physically walk to where it belongs on the line, then identify which decade marker (310, 320, etc.) they're standing closest to. This full-body representation makes "nearest ten" visceral.
Practical Notes
TIMING
Plan for 10-15 minutes per game, with 3-5 minutes for setup (distributing materials, drawing initial cards, recording targets). Don't rush setup—students need time to write targets in correct sections and organize their initial hand. Second and third rounds move faster as students internalize the procedures.
GROUPING
Works best with 1-2 players per game mat. Solo play builds individual fluency and faster decision-making. Pairs create natural peer verification—students can check each other's rounding and discuss which digits matter for different targets. Larger groups make turn-taking too slow.
MATERIALS & SPACE
Each player needs desk space for their game mat (flat and accessible) plus room to spread their five cards. Card visibility matters—students who can see all five options simultaneously spot winning combinations faster. The mat should clearly distinguish "round to tens" and "round to hundreds" sections to prevent target misclassification.
COMMON ERRORS
Watch for students who: (1) Write targets in wrong sections, mixing up tens and hundreds. (2) Look at the wrong digit when verifying—checking the tens digit when rounding to tens instead of the ones digit. (3) Don't recognize qualifying ranges, thinking only one specific number rounds to each target. These errors reveal gaps in understanding which place values control rounding.
ASSESSMENT EVIDENCE
Look for strategic sophistication over multiple rounds: Do students recognize which targets have wider qualifying ranges? Can they quickly identify the deciding digit for different target types? The completed game mat provides evidence—check whether all targets are in correct sections with proper place value alignment. Listen for unsolicited observations ("Oh, 500 is way easier than 340!") as evidence of emerging pattern recognition.