Foundations Sampler 2024

Subtracting 3-digit numbers with one regrouping Subtracting with Regrouping B1 Lesson Plans 48 200 190 180 170 160 150 140 METERS ©MathTeachersPress, Inc.Reproduction by anymeans is strictly prohibited. 48 Remember to show more ones when needed.Subtract. 1. 473 – 29 ______ 5. 472 – 154 ______ 2. 561 – 39 ______ 6. 583 – 365 ______ 3. 350 – 24 ______ 7. 970 – 721 ______ 4. 646 – 28 ______ 8. 450 – 235 ______ A B C D 674 –136 ______ A 448 B 810 C 542 D 538 10. The school library has 752 books. There are 218 books checked out. Howmany books are still in the library? _______ Strategies: Find the Pattern 9. Maren’s book has 173 pages. She has read 58 pages.How many pages does Maren have left to read? ________ The Great Pyramid of Giza was built about 2580 BC and was 147 meters tall.It was the tallest structure in the world for many centuries.The Gateway Arch in St.Louis, Missouri, is the tallest monument in the USA.It is 192 meters tall.How much taller is the Gateway Arch than the Great Pyramid? To compare numbers, we subtract. Butwe cannot take 7 ones from2 ones, sowewill need to regroup beforewe subtract. Hundreds Tens Ones 192 –147 ______ 45 meters 8 12 444 318 522 218 115 pages 534 books 326 249 618 215 Objective: To subtract 3-digit numbers with one regrouping. Materials: Base ten blocks, Place Value Mats (Masters 1 and 2) The Shark Swimathon, Murphy, Stuart J. (Activity 48) Subtraction of 3-Digit Numbers Write on the board: You have $42 to spend at the mall.You buy a pair of jeans for $26. How much do you have left? Have students build 42 on Place Value Mats. Can you remove 6 ones from 2 ones? (No, you must trade 1 ten for 10 ones.) Demonstrate the solution. Read the answer from the blocks. ($16) Write on the board: There are 362 workers in a factory. 125 of them have eaten lunch. How many have not eaten lunch? What are we asked to find in this problem? (how many have not eaten lunch) How do we find how many are left? (subtract or take away) Write 362 – 125 in vertical format on the board. Ask students to build the larger number on their mats. How many ones must be taken away? (5) Can you remove 5 ones from 2 ones? (no) What must we do? (exchange 1 ten for 10 ones) Now how many ones do we have? (12) Can we remove 5 ones from 12 ones? (yes) How many ones are left? (7) How many tens must be taken away? (2) Can we remove 2 tens from 5 tens? (yes) How many tens are left? (3) Can we remove 1 hundred from 3 hundreds? (yes) How many hundreds are left? (2) What number is left on the Place Value Mat? (2 hundreds 3 tens 7 ones or 237) Work this problem on the board, discussing each step. Note that the exchange of 1 ten for 10 ones is called regrouping or exchanging and is sometimes referred to as borrowing. Make up problems related to 845 – 261 and 936 – 347. Write each word problem on the board. Have students build the larger number and remove like blocks found in the smaller number. Show how the exchange is recorded when the problem is worked with paper and pencil. Read to Me Together, read the information at the top of the page and discuss the solution. Give students a helpful reminder of the 3 Bs, “When the Bottom number is Bigger, you Borrow.” Have students complete the page on their own. A student who chose A regrouped 1 hundred as 10 ones instead of regrouping 1 ten as 10 ones. Response C shows the result obtained if a student simply subtracted the smaller digits from the larger digits. Response D shows the answer if a student added instead of subtracted. Have students use base ten blocks to work the problem correctly. Then discover the error they made by comparing the correct answer to the incorrect answer. S KILL B UILDERS 15-8, 15-9 ERRORANALYSIS TestPrep B1 Lesson Plan Test Prep—Error Analysis A student who chose A regrouped 1 hundred as 10 ones instead of regrouping 1 ten as 10 ones. Response C shows the result obtained if a student simply subtracted the smaller digits from the larger digits. Response D shows the answer if a student added instead of subtracted. Have students use base ten blocks to work the problem correctly. Then discover the error they made by comparing the correct answer to the incorrect answer. ERRORANALYSIS TestPrep 31