Grade 5: Rounding

Warm up with a quick recall on the board. Use a number line to see which ten/hundred a number is closest to. Underline the rounding digit and check the digit to its right.

Rounding replaces a number with a nearby 'friendly' number, usually the nearest ten or hundred. 47 rounds to 50; 432 rounds to 400. It powers estimation: rounding first makes mental checks quick, and it is how we sense whether an exact answer is reasonable. Model the method clearly, thinking aloud:

• Start on a number line: mark 47, then ask which ten it is closer to (40 or 50). Distance, not rules, comes first.
• Once 'closer to' is secure, teach the digit rule: look at the digit to the right of the place you're rounding to, 5 or more rounds up, 4 or less keeps it down.
• Practise the awkward middle case: 45 rounds UP to 50 by convention.
• Move to hundreds and thousands only when tens are automatic.
• Use it for real: estimate shopping totals or sums (298 + 51 is about 300 + 50).

Do the first few questions of the practice worksheet together, one child explaining each step. Check for understanding before releasing the class to work alone.

Students complete the worksheet independently. Hand out the three difficulty levels below so every child works at the right stretch.

Circulate and look for these, they are the usual sticking points:

• Rounding the wrong digit (looking at the tens when rounding to the nearest hundred).
• Changing digits to the left as well as the right (473 to the nearest ten is 470, not 500).
• Thinking 45 can round down, by convention 5 always rounds up.
• Rounding after calculating instead of before, when the point is estimating.
• Rounding to the wrong place, and the exact-halfway case (5 rounds up) being applied inconsistently.

Pull the class back together. Ask one child to explain rounding in their own words, pose a single check question everyone answers on a mini whiteboard, and name what you will build on next lesson.

Use the independent worksheet as the evidence. A child who can complete it accurately and explain one answer has met the objective; anyone who cannot needs the easier level and a short reteach next session.