Free physical science lesson · Middle and high school

The Case of the $125 Million Unit Mix-Up

In 1999 a NASA spacecraft was lost at Mars because one team worked in pound-force seconds and the other expected newton-seconds. A no-prep lesson on the metric system and unit conversions with a self-grading Google Form. Students finish in about 25 minutes and you get the grades automatically.

Get the free lesson

Enter your email and the lesson opens right here: the force-copy link to the Google Form plus the printable lesson plan.

Get the lesson instantly, plus a monthly note with a new free resource. Unsubscribe any time.

Your free lesson is ready

Click below and choose Make a copy. The form lands in your own Google Drive, so your students' responses stay in your account.

Get the Google Form Lesson plan and standards (PDF)

Bookmark this page to come back any time. Next month's free resource will come to your inbox.

What students do

  1. Learn. A phenomenon hook and a short reading tell the story of the Mars Climate Orbiter, then the form teaches metric prefixes and how to convert between units step by step.
  2. Review. Students analyze a real data graph and use an interactive PhET simulation, then report back what they found.
  3. Try. Auto-graded questions give instant feedback, and a short claim-evidence-reasoning response asks students to explain what single habit would have saved the spacecraft.

The numbers behind the case

What happenedValue
Conversion that was missed1 pound-force second = 4.45 newton-seconds
Size of the error in each thruster reportabout 4.45 times too small
Planned altitude for entering Mars orbitabout 140 to 150 km
Altitude the spacecraft actually reachedabout 57 km
Cost of the spacecraftabout $125 million

What's included

How to use it

Open the link, click Make a copy, and assign the copy through Google Classroom or share the link directly. In the form, turn on Settings, then Quizzes, then Release grade immediately so students see their score. Grades appear in the form's Responses tab.

This is case 3 of 32

The full Physical Science bundle covers the whole course in the same format: science foundations, motion and force, energy, electricity and magnetism, waves, matter, atomic structure, bonding and chemical reactions. Every lesson is a self-grading Google Form with a phenomenon, real data and a PhET simulation.

See the 32-lesson bundle