Adam says, “0.25 is smaller than two-fifths.” Explain why he is correct.
If Adam is correct, we know that 0.25 is smaller than two-fifths. We just need to explain why. Adam’s statement is comparing a decimal number to a fraction. To help us compare these two numbers, we could make them both decimals.
To help us write two-fifths as a decimal, we need to change it into tenths. To get from five to 10, we need to multiply by two. So we need to do the same to the numerator or the number on top. Two times two is four. Two-fifths is equal to four-tenths. And we can write this as 0.4. The four digit represents the four-tenths.
Now we need to explain why Adam is correct. We could simply say two-fifths is equal to 0.4. 0.4 is greater than 0.25. Or we could say two-fifths is equal to 0.4, and 0.25 is less than 0.4. We could also explain that 0.25 is equal to a quarter, and one-quarter is less than two-fifths.