Alright, math time! This lesson is all about getting comfortable with the standard algorithm for adding and subtracting bigger numbers - three-digit and four-digit numbers, with regrouping. If your child has a solid foundation with two-digit addition and subtraction, they are ready for this.

What We Are Working On

The standard algorithm is the traditional method of stacking numbers vertically and working from right to left, column by column. The key skill at this level is regrouping (some of us grew up calling it "carrying" and "borrowing").

• In addition, when a column adds up to 10 or more, you regroup by carrying to the next column
• In subtraction, when the top digit is smaller than the bottom digit, you regroup by borrowing from the next column

Start with a Quick Review

Before diving into bigger numbers, do two or three two-digit problems together as a warm-up: - 47 + 38 - 82 - 56

Make sure your child can explain what they are doing at each step. If they just get the right answer but cannot explain the regrouping, slow down and talk through it.

Level Up: Three and Four Digits

Now try these, working through them step by step:

Addition: - 1,247 + 856 - 3,489 + 2,675

Subtraction: - 4,003 - 1,587 - 2,310 - 948

For each problem, have your child: 1. Write the numbers stacked vertically, lining up the place values 2. Start in the ones column and work left 3. Show ALL regrouping (the small numbers written above) 4. Check their answer (for subtraction, they can add their answer to the bottom number to see if they get the top number)

Real-World Tennessee Problems

Here is where the fun comes in. Use real numbers from our state:

Distance problems: - Maryville to Nashville is about 188 miles. Nashville to Memphis is about 212 miles. How far is it from Maryville to Memphis going through Nashville? (188 + 212 = 400 miles) - The distance from Knoxville to Chattanooga is about 112 miles. The distance from Knoxville to Bristol is about 122 miles. How much farther is Bristol? (122 - 112 = 10 miles)

Population problems: - The population of Maryville is about 29,800. The population of Alcoa (our neighbor) is about 10,000. What is the combined population? (39,800) - Knoxville has about 192,000 people. Maryville has about 29,800. How many more people live in Knoxville? (162,200)

These kinds of problems make the math feel real and connected to places your child actually knows.

Tips for Success

• Use graph paper. Keeping digits aligned in columns prevents so many errors. Each digit gets its own square.
• Always estimate first. Before solving 3,489 + 2,675, have your child round and estimate: about 3,500 + 2,700 = 6,200. Then they solve it exactly and check if their answer is close to the estimate.
• Show your work. I know kids want to do it in their heads, but writing out the regrouping helps them catch mistakes and builds good habits for harder math later.

Daily Practice

Do 4-6 problems a day for a week, mixing addition and subtraction. Short, consistent practice builds fluency much better than one long session. And whenever you can, use real numbers - grocery totals, sports scores, distances on road trips. Math is everywhere once you start looking for it!