Examples of Incorrect Answers
How the Mistakes are Made
Misconception Explained
In this math misconception, when the sum of two single digits exceeds 10, the value of the resulting ten’s digit is improperly combined with the sum of the tens digits; instead, it is holding the ten’s digit by itself and pushing the value of the ten’s digit from the sum of two ten’s digits to the hundred’s place.
Concepts Invovled
- Place Value
Discussion Questions
Example
Questions to Ask
- What does the 2 in 26 mean? (two tens)
- What does the 6 in 26 mean? (six singles)
- What does the 8 in87 mean? (eight tens)
- What does the 7 in 87 mean? (seven singles)
- When we add 26 and 87, how many singles are we adding? (6 and 7)
- What’s the sum of 6+7? (13)
- What does that 1 mean in the sum 13? (one ten)
- What does that 3 mean in the sum 13? (three singles)
- When we add 26 and 87, how many tens are we adding? (2 and 8)
- What’s the sum of 2 tens and 8 tens? (10 tens)
- How many tens are there altogether now? (11 tens: 10 tens from 2+8 tens and one ten from 6+7)
- How much is ten tens equal to? (100)
- How should we write 11 tens? (110)
- How should we write 11 tens and 3 singles? (113)
