A student who fails to understand that fractions are numbers on a line will struggle with algebra in 8th grade. That student will likely avoid calculus in high school. That student might close the door to engineering forever.
Conversely, a student who conquers the 5th-grade bridge develops mathematical maturity . They learn that confusion is not failure—it is the first step of learning. If your child is in the 5th grade right now, do not panic if they cry over denominators. Do not rush to give them the answer.
Instead, ask them: "Show me where you got stuck."