The Ball-Pit Asteroid

About this resource

In 2020, NASA’s OSIRIS-REx spacecraft gently touched asteroid Bennu, and its arm sank in like a hand in a ball pit. What holds a pile of loose rubble together in space, and why does it hold so weakly? Gravity always pulls. Every object with mass pulls on every other, and more mass means a stronger pull. In this one-week, 5-level Gravity Depends on Mass unit for middle school science (NGSS MS-PS2-4), students investigate a real mystery, then use their evidence to crack the case.

The Ball-Pit Asteroid is part of Science Unlocked, a series of mystery-driven lesson sets. Every set opens with a real, surprising phenomenon, builds the science one level at a time, and ends with students solving the mystery in a claim-evidence-reasoning (CER) write-up.

Topics: gravity, claim evidence reasoning (CER), science phenomenon, review games.

What's included

• Teacher Deck (86 slides, PowerPoint). Answers are highlighted on the slides. Speaker notes tell you what to say and do, what to watch for, and how to support students or push GT students further. Prep slides and answer keys are hidden, so they skip during a slideshow.
• Interactive Student Deck (52 slides, PowerPoint + PDF). Students type in boxes, drag cards and check marks, and rate their confidence. Assign one copy per student in Google Classroom or your LMS.
• Google Slides versions of both decks. Click a button in the Google Slides Links PDF to make your own copy in Google Drive.
• Teacher Guide (24-page PDF). The standard, a week at a glance, a materials list, misconceptions to watch for, a run-of-show for every level, answer keys and sources.
• Student Printable (17-page PDF + a low-ink greyscale copy). The same tasks on paper in 12 pt type, for students without devices, sub days, or anyone who learns better with a pencil. Slide numbers match the Student Deck.
• Self-grading digital activity. SCORM 2004 and SCORM 1.2 packages for an LMS that accepts SCORM uploads, a web package, and a single HTML file that opens in any browser. Notes, sorts, matches, tables and multiple-choice items grade themselves, and students get a copy-and-paste backup of their work. A 2-page teacher quick start is included.
• Two whole-class review games that open in any browser: a Jeopardy-style game (6 categories, 30 clues) and Trashketball, where teams answer on whiteboards and then shoot for points.
• Kahoot! and Blooket import files. 48 review questions, one file per level plus an all-levels file, with a printable answer key.
• Start Here guide, HTML & SCORM how-to guide and Terms of Use, so you know which file to open first.

The 5 levels (about one 45–50 minute class each)

1. Gravity Pulls. Gravity is a non-contact force that always attracts, two objects pull on each other. Key activities: Ball-Pit Asteroid mystery, Bennu case file, Fact-or-Myth sort.
2. More Mass, More Pull. Mass vs. weight, empirical evidence: more mass leads to more pull. Key activities: Mass and Pull Lab (spring scales), Lab Conclusion CER.
3. Both Masses Matter. The pull depends on BOTH masses, tiny unless one mass is huge. Key activities: Gravity simulation data, Cavendish 1798, NASA planet-pull data.
4. Make Your Case. System model, claim, evidence, reasoning, refute a myth, present. Key activities: Earth–ball system model, evidence sort, Gravity Court presentations.
5. Crack the Case. Stretch HS-PS2-4: Newton’s law of gravitation (mass × mass, distance²). Key activities: Predict-the-pull table, Stretch CER, final Crack the Case CER.

Built for real classrooms

• Every level follows the same routine: "I can" targets with a confidence check, a warm-up, copy-it notes with a word bank, hands-on practice, a checkpoint students must pass to unlock the next step, and an exit ticket. A 10-item Mini Quiz wraps up the week.
• Level 1 opens with a Power-Up on the earlier-grade ideas this standard builds on (3-PS2-1, 5-PS2-1, 5-PS1-2).
• The last level includes a high school Stretch (HS-PS2-4) that every student tries and advanced students can take further.
• Hands-on lab (Mass and Pull Lab). Student materials list: Spring scale that reads in newtons (0–10 N); Hooked masses: 100 g, 200 g, 300 g, 500 g; A mystery object (shoe, water bottle, or stapler); Ring stand or hook (optional); Goggles. Safety notes are on the slides and in the Teacher Guide.
• Support is built in: word banks, sentence starters and support notes on the slides, plus GT extensions.

Standards

• NGSS MS-PS2-4: Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects. (Kentucky 6-PS2-4 uses the same wording.)
• SEP: Engaging in Argument from Evidence · DCI: PS2.B · CCC: Systems and System Models
• Stretch: HS-PS2-4
• CCSS connections: 6.RP.A.3, SL.6.4, SL.7.4, WHST.6-8.1

Try the digital activity first

• Not sure the self-grading activity will work in your LMS? Download the FREE HTML & SCORM Sample and test it with your students before you buy.

Save with a bundle

• Forces, Gravity & Magnetism (5 sets)
• Middle School Physical Science + Engineering (23 sets)
• Science Unlocked Mega Bundle (all 89 sets)

Teach next

• The Bouncing Lander (MS-PS2-1)
• The Plane Pull (MS-PS2-2)
• The Magnet Express (MS-PS2-3)
• The Floating Frog (MS-PS2-5)

More from Mystery Lab Learning

• See every Science Unlocked set, and follow to hear when new ones are added, at Mystery Lab Learning.

Good to know

• The illustrations in this resource were created with AI image tools, and AI tools helped draft the lesson text. Every slide, answer key and lab step was then fact-checked against the sources listed in the Teacher Guide and proofread.
• Kahoot!, Blooket, Jeopardy!, Google Slides and PowerPoint are trademarks of their owners. This resource is not affiliated with or endorsed by them.
• License: one teacher, for use with their own students. Please buy an additional license for each colleague who uses it.