Strategy Showdown Warmup
Do Now 10 Minutes Recall & Practice
Strategy Showdown Warmup
Name:
Date:
Part 1 • Recall 28 + 15 = ?
Solve this problem using all 4 strategies from last night's work:
1
Tens Blocks & Ones
Draw rods (|) & cubes (■)
Draw 28 and 15. Circle 10 ones to regroup into a ten!
Tens (Rods) Ones (Units)
Tens: ___ Ones: ___ Total = _____
2
Open Number Line
Jump Strategy
Start at 28. Jump tens (+10) then ones (+2, +3 or +5).
Show Jumps Above Line
28 ... ?
Jumps: +___ +___ Total = _____
3
Tally Marks in 5s
Bundling Fives
Draw tallies in groups of 5 for 28 and 15, then count by 5s.
28 Tallies 15 Tallies
Groups of 5: ___ Extras: ___ Total = _____
4
Standard Algorithm
Vertical Columns
Align place values. Regroup tens into the small box.
Tens Ones
2 8
Part 2
Pick Your Favorite Strategy!
Which one felt easiest or fastest for you?
1. Circle your favorite:
A. Tens Blocks B. Number Line C. Tally Marks D. Standard Algorithm
2. Use your chosen strategy to add: 72 + 34 Show your work below
Strategy I used: _______________________________
72 + 34 =
Strategy Showdown Teacher Guide
Teacher Guide 10-Minute Launch Grades 2–3 • Addition Strategies
Strategy Showdown Teacher Guide
Step-by-step launch, pacing prompts, and active circulating guide for new educators.
Target Problem
28 + 15 = 43
Application: 72 + 34 = 106
Pre-Bell Prep:
Warmup face-down on desks 10:00 visual timer ready Base-ten blocks accessible
0:00 – 1:30
The Hook & High-Urgency Launch
Goal: 100% Pencil-to-Paper
Say This Verbatim:
“Mathematicians, flip your papers in 3... 2... 1! Today is our Strategy Showdown. For the first 6 minutes, your mission is to solve 28 + 15 using all 4 methods we mastered this week. We are in 100% silent solo sprint mode. If you finish Part 1, move directly into Part 2 to pick your champion strategy. Your timer starts now!”
Do Not: Model or pre-solve any quadrant on the board. Let students grapple first.
Do: Immediately start the 10-minute timer on screen and circulate silently.
1:30 – 6:30
Silent Solo Sprint & Circulating Laps
Focus: Active Observation
1 Lap 1: Urgency & Tool Setup (1:30–3:00)
Walk the perimeter briskly. Ensure every student has written their name and initiated Quadrant 1 (Tens Blocks) or Quadrant 4 (Algorithm). Tap desks of hesitating students.
Whisper prompt: “Start with rods and cubes for 28. How many rods? Draw them first.”
2 Lap 2: Regrouping Check (3:00–6:30)
Look specifically at the regrouping moment: 8 + 5 = 13 ones. Check if they circled 10 ones in Q1, showed friendly jumps in Q2, or placed the 1 ten in the top box in Q4.
Praise prompt: “I love how clearly you circled your ten bundle here.”
6:30 – 8:30
Part 2: Favorite Strategy Transfer
Apply to 72 + 34
30-Second Transition Announcement (at 6:30):
“Check your timer—3 minutes remaining! Even if you are finishing your last quadrant, drop your eyes down to Part 2. Circle the one strategy that felt cleanest or fastest for you, and use it to solve 72 + 34 in the big arena below!”
Notice which strategy students select when given autonomy. Students who struggled with tallies often switch to the standard algorithm or number line for efficiency.
8:30 – 10:00
Rapid Strategy Vote & Lesson Bridge
Total = 106
1. Quick 15-Second Fist-to-Four Vote:
“Hold up 1 finger for Blocks, 2 for Number Line, 3 for Tallies, 4 for Algorithm. Who was your champion for 72 + 34?” Scan the room to validate diverse thinkers.
2. Bridge to Today's Core Lesson:
“Notice how 28 + 15 needed regrouping in the ones (8+5=13), but in 72 + 34 our tens regrouped (70+30=100)! Today we will explore how our strategies hold up with 3-digit totals.”
Pro-Tip: Clip this sheet to your clipboard while walking Lap 1 & Lap 2. Page 1 of 2 • Turn over for Diagnostic Cheat Sheet
Diagnostic Playbook Circulation & Troubleshooting
Active Monitoring & Misconception Guide
Page 2 of 2
Quadrant Diagnostics: What to Spot & How to Prompt
Based on 28 + 15 = 43
1 Tens Blocks & Ones Key: Regrouping 10 Ones
Expected Work: 2 rods & 8 cubes + 1 rod & 5 cubes. 10 cubes circled to form a new rod (3 rods + 1 new rod = 4 rods, 3 cubes left = 43).
Common Misconception: Student leaves 13 individual cubes loose and writes "3 tens and 13 ones = 313" or counts wrong.
Fix: “Count your ones cubes. When you get to 10, circle them! What do 10 cubes turn into?”
2 Open Number Line Key: Jump Strategy
Expected Work: Start at 28. Jump +10 to 38. Then jump +2 to reach friendly landmark 40, and +3 to land on 43 (or jump +5 directly to 43).
Common Misconception: Student jumps backward or tries to make 15 single tick marks and loses accuracy along the line.
Fix: “Decompose 15 into tens and ones. Take one big jump of 10 first. Where do you land?”
3 Tally Marks in 5s Key: Skip Counting
Expected Work: 28 = 5 bundles of 5 plus 3 single tallies. 15 = 3 bundles of 5. Total: 8 bundles of 5 (40) + 3 singles = 43.
Common Misconception: Student draws unbundled single tally marks or forgets the 5th diagonal slash, making counting laborious.
Fix: “Bundle every 5 with a diagonal slash! How can we count all the bundles quickly? 5, 10, 15...”
4 Standard Algorithm Key: Place Value Alignment
Expected Work: Ones column: 8 + 5 = 13. Write 3 in ones place, carry 1 ten into the dotted box above tens column. Tens: 1 + 2 + 1 = 4.
Common Misconception: Student writes entire '13' in the bottom row (getting 313) or writes 1 at the bottom and carries 3 to tens.
Fix: “In the number 13, which digit is ones and which is tens? Send the ten up to the attic box!”
On-The-Fly Differentiation Strategies
Striving Learners (Cognitive Load Reduction)
- Reduce to 2 Quadrants: Whisper: “Focus on Quadrant 1 and Quadrant 4 today. Nail those two!”
- Tactile Manipulatives: Place 4 plastic tens-rods and 15 single cubes directly onto their desk for Q1.
- Number Line Bookmark: Provide a pre-printed 0–50 number line strip as an external reference.
Early Finishers (Deep Mathematical Thinking)
- Strategy Comparison: “Why is the tally strategy slower for 72 + 34 than 28 + 15? Write 1 sentence on back.”
- Decomposition Challenge: Can you solve 72 + 34 using partial sums? (70 + 30 = 100, 2 + 4 = 6 → 106).
- Reverse Check: Use subtraction (106 - 34) on a number line to verify their answer.
60-Second Debrief Script: The Power of Strategy Choice
Debrief & Transition
“Pencils down, eyes up in 3... 2... 1. Look at how many different ways our classroom solved the exact same problem. Some of us loved drawing base-ten rods because we can literally see the regrouping happen. Others loved the algorithm because it was fast and compact. Today in our math workshop, we will remember that great mathematicians don't just know how to calculate—they know how to pick the best tool for the job. Turn to page 12 in your math journal!”
Strategy Showdown • Lesson 1 Teacher Facilitation Resource Designed for 10-Minute Do Now Execution
