100 More Or Less: Maths Mental Maths Game & Number Sense — Activities (Year 3)

A quick, timed true/false quiz testing 100 more/100 less. Students are shown a starting number, an operation (+100 or -100), and a claimed result, then judge true or false before the clock runs out.

Whats inside

• 10 questions, 15 seconds per question
• True/false format: judge whether the claimed answer is correct
• Score and streak tracking with audio feedback

Why it works

• Time pressure builds genuine mental-maths speed, not just accuracy
• Self-contained single game, no setup, works on any device with a browser
• Quick enough for a starter or plenary activity