Physics Sensei questions & answers
Why Do I Understand the Material but Fail the Test?
In class, it all makes sense. Your professor works an example, and you follow every step. You nod along. You even think, “That’s not so bad.”
Then the test comes. You read the first problem and stare at it. Where do you even start? It’s like the test is written in a different language.
If you understand the material but fail the test, you’re not imagining it. You really do understand it. The test is just asking for one more step that class and homework almost never practice.
What’s really going on
Understanding physics comes in three steps. First, you understand an explanation when someone shows it to you. Second, you can use an idea when you’re told which one to use. Third, you can look at a problem and pick the right idea yourself.
Class teaches the first step. Homework practices the second. But the test checks the third: nobody tells you which idea to use. You have to decide.
Why homework hides the problem
Homework usually comes one chapter at a time. If this week is forces, every problem is a forces problem. You know the idea before you even read the question.
That makes homework feel smooth. But it means you never practice choosing. Then the test mixes forces, energy, and momentum together, and choosing is the whole game.
Why it’s hard to change
When you understand the explanations, it doesn’t feel like anything is missing. So there’s no reason to change.
And mixing chapters on purpose feels confusing. It’s slower than doing problems in order. That slow, confused feeling is exactly what the test feels like. Practicing it at home is how it stops being a surprise.
The fix: practice choosing, not just solving
You don’t have to solve more problems. You need to practice the one step the test checks most: deciding which idea a problem needs.
Try this before your next test: name the idea
- Pick 9 problems from three different chapters, like forces, energy, and momentum. Shuffle them so you don’t know which is which.
- Don’t solve them. For each one, write only two things: What are they asking? What’s the big idea? Add one reason, like “energy, because it gives a height and asks for a speed, with no time.”
- Give yourself about 1 minute per problem.
- Check your choices against the solutions. Did you pick the right idea?
- Fully solve only the problems where you picked wrong. Next time, mix in a new chapter.
Nine problems take about 10 minutes. And those 10 minutes practice exactly what the test asks for first.
What changes
At first, you’ll pick the wrong idea more than you’d like. That’s the point of practicing it now.
Soon you’ll start noticing clues. “At rest” and “how hard” point to forces. “How high” and “how fast” point to energy. “Collides” and “sticks together” point to momentum. Test problems start to feel like puzzles you know how to start.
Knowing the ideas isn’t enough. Practice picking them.
Practice problems built for this
On Physics Sensei, every problem is solved step by step, and the third step is always “What’s the big idea?” So every problem you try is practice at choosing. Each one asks you to try it first, then gives you one more like it, with new numbers. You find out right away exactly where you slipped.
Your next step: pick three problems from three different chapters on Physics Sensei. Before you open any steps, write down which big idea each one needs.
More questions about studying and grades? See them all here.
Raul, Physics Sensei
