Truncation Error Intervals | I Do, We Do, You Do | Year 10 Maths Foundation | Print Free

Teach error intervals for truncated numbers with this editable Year 10 Maths Foundation lesson. Pupils identify included lower bounds and excluded upper bounds, write intervals using inequalities and explain how truncation differs from rounding. The lesson focuses on positive numbers.

WHAT IS INCLUDED
• One editable 66-slide PowerPoint with answers.
• Six retrieval questions and six prerequisite questions, each with grouped answers.
• Key vocabulary and a number-line explanation of a truncation interval.
• Six I Do / We Do examples in three matched pairs, using different values and worked answers.
• Twenty individual AFL questions, each followed by its answer.
• Thirty-six whole-class practice questions on one slide, with answers on one slide.
• One differentiated page with 14 Developing, five Secure and four Greater Depth questions, plus one Super Challenge.
• All 23 differentiated answers together, followed by a separate challenge explanation.
• Three misconception checks with explained answers.
• An original six-mark exam-style question with answers and suggested marking points.
• Three exit questions, each followed by its answer.

MODELLING AND PRACTICE
The paired examples connect a truncated value to its interval, include upper bounds that cross an integer boundary, and reverse the process to recover a truncated value. Practice covers one, two and three decimal places, including changes across integer boundaries. A sequence asks pupils to identify the truncated value and decimal-place accuracy from a given interval.

DIFFERENTIATION WITH DEPTH
Developing includes decimal-place truncation and truncation to an integer. Secure asks pupils to recover accuracy, identify possible original values, convert bounds from kilograms to grams, count values restricted to multiples of 0.01 and identify possible rounded results. Greater Depth explores the absence of a greatest possible value, combines rounding and truncation conditions, connects two levels of accuracy and reasons about the amount by which a recorded length underestimates the original.

ONE SUPER CHALLENGE
An unknown number has one reported value after truncation and another after rounding to a different accuracy. Pupils find the interval satisfying both conditions, then determine every possible result of truncating the original number to two decimal places.

CHECK UNDERSTANDING
Misconceptions address confusing rounding with truncation, including an excluded endpoint and assuming truncation always changes a value. The exam-style task combines a capacity interval, conversion to millilitres and counting possible integer measurements. Exit checks revisit bounds, possible values and accuracy.

PRINT FREE AND PRACTICAL
Project the lesson while pupils answer in exercise books or on mini whiteboards. No printed worksheets are required. The whole class can use the differentiated slide together. Text and diagrams remain editable.

Year 10 Unit 19, U301. Original questions from Beyond Printables.