GRADE 2 · ALBERTAOUTCOME AB-G2-2N1
L1 · Estimating quantities with benchmarks
Learning goal
“I can estimate how many by comparing a set with a benchmark I know.”
Estimate — a good guess about how many, made on purpose, not a wild guess.
Benchmark — a known amount you compare with, like one full ten frame: 10.
About — close to a number, not exactly that number. "About 30" can be 29 or 31.
Worked example
A tray shows about 3 full ten frames of counters. Step 1: Name the benchmark: one full ten frame holds exactly 10. Step 2: Count the frames by 10s: 10, 20, 30. Step 3: The tray holds about 30 counters. "About," because an estimate is close, not exact.
Check yourself — explain it
Why is 'about 30' a good estimate here?
Paired problem — example still visible
A tray shows about 5 full ten frames. About how many counters? -> About 50.
Faded completion — last step is yours
"About 2 full ten frames of counters is about ___ counters." -> 20
Ready to practise?
10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.