Forces, Motion, Structures

This is lesson 4 of 10 in the unit "Manitoba Science Year Overview". Lesson Title: Forces, Motion, and Structures Lesson Description: Weeks 11–14; approximately 8 lessons. Essential questions: How do forces change motion? What makes a structure stable, strong, and efficient? Key concepts: pushes and pulls, gravity, friction, balanced and unbalanced forces, speed, load, tension, compression, shape, stability, materials, and simple machines. Manitoba alignment: Grade 5 Forces and Simple Machines; Grade 7 Forces and Structures; related Grade 6/8 expectations involving flight, motion, design, and problem solving. Investigation/design challenge: test friction on different surfaces, measure toy-cart motion, and design a bridge, grain-bin support, winter shelter, or accessible ramp using limited materials. Vocabulary: force, friction, gravity, mass, motion, speed, balanced, unbalanced, load, tension, compression, beam, truss, lever, pulley, stability. Formative assessment: force diagrams, prediction-and-test tables, prototype conferences, and peer feedback using a design rubric. Summative assessment: tested structure or simple-machine portfolio including revisions and evidence. Success criteria: I can identify forces, explain how materials and shape affect performance, use measurements to compare designs, and justify revisions. EAL/diverse supports: gesture-based demonstrations, labeled diagrams, manipulatives, preteaching of mathematical language, accessible building tools, partner roles, and multiple prototype formats. Extension: optimize strength-to-mass ratio, investigate wind or snow loading, or use a spreadsheet to graph performance. Local connections include bridges, tractors, snowmobiles, wheelchair access, farm machinery, grain elevators, and winter construction.

Overview

Lesson 4 of 10 in the “Manitoba Science Year Overview” unit. Students investigate how pushes, pulls, gravity, and friction affect toy-cart motion, then apply their findings to a short bridge-design challenge. Groups use measurements and force diagrams to justify one design decision.

Learning intentions

Students will be able to:

Identify pushes, pulls, gravity, friction, and balanced or unbalanced forces.
Predict and measure how surface type affects a toy cart’s motion.
Use tables and simple measurements to compare results.
Explain how shape, materials, and load affect a structure’s stability.
Communicate a design revision using evidence from testing.

Success criteria

I can draw arrows to show the main forces acting on a moving cart.
I can make a prediction and record measurements using consistent units.
I can explain how friction, shape, or materials affected performance.
I can use evidence from a test to justify a design revision.

Curriculum links

Developing and using models to represent forces and motion.
Planning and carrying out fair tests, recording observations, and analyzing data.
Applying science and engineering ideas to design, test, and improve a structure.
Common Core mathematical practices: making measurements, representing data, comparing quantities, and explaining reasoning with evidence.
Common Core literacy practices: asking and answering questions, writing informative explanations, and participating in collaborative discussions.

Lesson structure (60 minutes)

0–7 minutes – Engage: What makes motion change? Open with the hook and lesson introduction slides. Show a toy cart moving on a smooth floor and stopping on a rough surface. Ask: “What forces are acting, and why does the cart stop?” Students quietly predict, then share with a partner. Introduce the lesson goals and connect examples to tractors, snowmobiles, bridges, and wheelchair ramps.
7–15 minutes – Build the force model Use the force diagrams and vocabulary slides to review force, motion, gravity, friction, balanced, and unbalanced forces. Demonstrate a push and pull, using gestures and arrows. Students use the Forces Arrow Diagram Cards in pairs to match force names, definitions, illustrations, and arrow directions. Model a simple cart diagram: applied push forward, friction backward, gravity downward, and surface support upward.
15–20 minutes – Plan a fair test Place students in groups of four with roles: materials manager, pusher, timer/measurer, and recorder. Distribute the forces and motion investigation sheet. Groups predict which surface will let a cart travel farthest or fastest. Identify the independent variable (surface), dependent variable (distance or time), and controls such as the same cart, starting point, and push. Emphasize safe, gentle pushes and consistent units.
20–34 minutes – Investigate friction and motion Groups test the cart on three available surfaces, such as smooth floor, cardboard, fabric, or carpet. They complete at least two trials per surface, recording distance traveled after a marked push or the time needed to travel a set distance. Circulate and ask: “What evidence shows friction changed the motion?” Students use the investigation procedure and safety slides for the testing sequence and discussion prompts.
34–40 minutes – Analyze and explain Groups calculate or compare averages where appropriate and identify the surface with the greatest friction. Students add arrows to a cart diagram on the forces and motion investigation sheet and write a two-sentence explanation using “because.” Invite two groups to share results. Clarify that friction can be useful for braking and grip, but can reduce motion when surfaces rub.
40–54 minutes – Mini design challenge: stable bridge Give each group limited materials, such as index cards, paper, tape, and craft sticks. The challenge is to span a 30-centimeter gap and hold as many washers or blocks as possible for 10 seconds. Before building, groups sketch a design and label the load, compression, tension, beams, and supports where they can. Use the bridge challenge instructions and design prompts. Test once, record the load held, then make one evidence-based revision. Remind students that triangles, folded beams, wide bases, and distributed loads may improve stability.
54–60 minutes – Share and assess Groups briefly report: “Our structure held ___ because ___; we revised ___ because ___.” Use the reflection and exit-question slides to guide the discussion. Students complete the final reflection on the forces and motion investigation sheet: identify one force, one measurement, and one justified design revision. Collect worksheets and note misconceptions for the next lesson.

Resources

the forces, motion, and bridge investigation deck
the forces and motion investigation sheet
the Forces Arrow Diagram Cards
Toy carts or small wheeled vehicles
Three contrasting floor or tabletop surfaces
Metersticks or rulers, stopwatches, and masking tape
Index cards, craft sticks, paper, tape, washers, or small blocks
Chart paper or board
Safety scissors, if needed
Optional photographs of local bridges, grain elevators, ramps, or winter structures

Assessment

Observe force-arrow matching, predictions, role participation, and accurate use of measurement units.
Check investigation tables for a prediction, repeated trials, controlled variables, and a reasonable comparison.
Assess the bridge explanation for identifying forces, using evidence, and justifying a revision. Record students needing support with friction, force direction, or data interpretation.

Differentiation

Provide gesture-based demonstrations, labeled diagrams, picture-supported vocabulary, and sentence frames such as “The cart moved farther on ___ because ___.”
Pair EAL students with supportive peers and preteach mathematical language including distance, time, faster, slower, average, and evidence.
Offer accessible building tools, larger materials, pre-marked measurement lines, and flexible roles for students with motor, attention, or sensory needs.
Support younger or less confident students with a partially completed table and a choice of force arrows; extend advanced students by calculating averages, graphing results, or optimizing the bridge’s strength-to-mass ratio.