Strip Diagrams
The school library has 450 books. 180 are checked out. Draw a strip diagram and solve.
450 is the whole (top bar). One part is 180, but we do not know the other
Equation: $450 - 180 = $270
You start at 235 on an open number line and take jumps of +100, +40, and +3. What number do you land on?
378
A student models a number with 3 hundreds flats, 14 tens rods, and 6 ones blocks. What is the number after trading 10 ten rods.
446
Solve: 479 + 384. Make sure to show all regrouping marks!
863
The school cafeteria bought 350 apples. On Monday, students ate 120 apples. On Tuesday, students ate 90 apples. How many apples are left?
140 apples
Maya has 234 stickers. Lucas has 165 stickers. How many more stickers does Maya have than Lucas? Draw a strip diagram and solve.
234 + 165 = 399
Subtract 512 - 234 on a number line. Then write your answer.
278
To model $534 - 217$ with blocks, you must regroup first. Describe the exact block trade you need to make before subtracting ones.
Trade 1 ten rod for 10 ones blocks (leaving 5 hundreds, 2 tens, 14 ones).
Solve: 603 - 248. Show how you regroup across the zero.
355
Ben has 145 baseball cards. His brother gives him 75 more cards. Then Ben sells 50 cards to a friend. How many cards does Ben have now?
170 cards
A farmer harvested 600 apples. He sold some and has 215 left. How many apples did the farmer sell. Draw a strip diagram and solve.
600 - 215 = 385
Leo had 520 arcade tickets and spent some on a prize. Now he has 385. Show how to jump backward on a number line from 520 to find how many he spent.
answer: 135 tickets
You have 4 hundreds flats and 0 tens rods. You need to subtract 5 tens. What trades must you make?
Trade 1 hundred flat for 10 tens rods first.
Spot the mistake! A student solved 500 - 163 and got 447. What did they do wrong?
They subtracted 3 - 0 and 6 - 0 instead of regrouping across zeros (500 - 163 = 337).
A toy store has 600 video games. They sold 238 games on Saturday and 185 games on Sunday. Draw a strip diagram with 3 sections or write an equation to show how many games are left.
177 games left
A bakery made 500 cookies. 180 were chocolate chip, 140 were oatmeal, and the rest were sugar. Draw a strip diagram with 3 parts and solve for the sugar cookies.
whole = 500
part = 180
part = 140
180 + 140 = 320
500 - 320 = 180
Solve 435 - 198 on an open number line.
237
Construct the block model for 603 - 248. What is the final answer?
3 hundreds, 5 tens, and 5 ones
355
Solve: 700 - 428.
272
Third grade collected 425 aluminum cans for recycling. Fourth grade collected 150 more cans than third grade. How many cans did fourth grade collect, and how many did both grades collect altogether?
fourth grade = 575 cans
altogether - 1,000 cans
Explain how looking at a strip diagram tells you whether to add or subtract to find a missing number.
If the total/whole is missing, you add the parts together. If a part is missing, you subtract the known part from the total.
Solve 382 - 145 on an open number line.
Why do we say 10 tens = 1 hundred and 10 ones = 1 ten? Explain how this rule helps when subtracting across zero.
Our number system is Base-10. When a column doesn't have enough units to subtract from, we break down 1 larger unit into 10 of the next smaller unit.
Multi-step challenge --> Sam had 700 marbles. He gave 243 to Alex and 185 to Taylor. How many does he have left?
272
DAILY DOUBLE!!!
Maya wants to buy a bicycle that costs $320. She has saved $145. Her grandmother gives her $85 for her birthday. How much more money does Maya need to buy the bicycle?
$90 more