The first question asked, "Is this possible?" Now we will ask, "Does this make sense?" There are times when even though the answer is possible, it just doesn't make any logical sense. Let's look at another attempted solution for the example from section 1.

Johnny is 24 years younger than his dad. If Johnny's dad is currently 30 years old, how old is Johnny?

Solution:

Given: Johnny's dad is 30.

Question: How old is Johnny?

Plan: I should add 24 to Johnny's dad's age to find Johnny's age.

Equation: J = 30 + 24

Calculator:

Modified from: SharpEl-5120, EpiVictor, Wikimedia Commons

Answer: J = 54

Is this a possible age for someone?

Interactive popup. Assistance may be required. Check Your Answer Yes

Is this answer reasonable?

Interactive popup. Assistance may be required. Check Your Answer No

Why or why not?

Interactive popup. Assistance may be required. Check Your Answer This answer says that Johnny is older than his dad. Johnny can't be older than his dad.

Where is the mistake in the solution?

Interactive popup. Assistance may be required. Check Your Answer This student wrote the wrong plan.