Crystal Growth Exploration

Overview

This 55-minute science session for Year 3 students explores how crystals grow through dissolving and evaporation processes. It aligns closely with the New Zealand Curriculum Refresh, focusing on understanding solids, liquids, soluble solutions, and changes in states of matter. Students will actively engage in making predictions, observations, and explanations using scientific vocabulary.

Curriculum Alignment

Science Capability & Strand:

Nature of Science / Investigating in Science:
- Make and record observations with guidance
- Ask questions, make predictions, and carry out simple investigations
Living World / Material World:
- Understand observable properties of materials and simple changes they undergo
Level 2 Science Achievement Objectives (approx. Year 3):
- Explore and describe physical properties of common materials
- Investigate changes caused by mixing and evaporation

Key Competencies

Participating and contributing: collaborate in groups during investigations.
Thinking: make predictions, test ideas, and reflect on observations.
Using language, symbols, and texts: communicate scientific ideas clearly.

Learning Intention

Students will observe and describe how crystals form from a soluble solution, make predictions about this process, and explain changes in the states of matter involved.

Success Criteria

✔ I can explain what a solid and a liquid are.
✔ I can describe what happens when a solid dissolves in a liquid.
✔ I can predict what might happen when the liquid evaporates.
✔ I can observe and describe how crystals grow over time.

Key Concepts and Vocabulary

Concept	Vocabulary
States of matter	Solid, liquid
Dissolving and solutions	Dissolve, solution, soluble, insoluble
Changes in matter	Evaporation, crystallization, crystal
Scientific skills	Prediction, observation

Resources Required

Table salt or sugar (solute)
Warm water (solvent)
Clear plastic cups or jars (one per pair)
Spoons for stirring
String and pencils (for growing crystals on)
Observation recording sheets or science notebooks
Visual aids: diagrams/photos of solids, liquids, crystals

Lesson Sequence

1. Introduction (10 minutes)

Begin with a brief interactive discussion: “What do you think solids and liquids are?” Use everyday objects to show examples.
Explain that today we will see what happens when a solid dissolves in a liquid and how crystals can grow.
Introduce key words with simple definitions and visuals: solid, liquid, dissolve, solution.
Show a quick demonstration by dissolving salt/sugar in warm water.

2. Making Predictions (5 minutes)

In pairs, students predict what they think will happen when the water evaporates.
Model prediction language: “I think the water will... because...”
Students record their predictions on recording sheets with sentence starters if needed.

3. Investigation Setup (15 minutes)

Guide pairs to mix a measured amount of salt/sugar into their warm water cups until no more will dissolve—creating a saturated solution.
Show how to hang a string suspended on a pencil into the solution for crystals to grow on.
Encourage careful stirring and observing the solution’s clarity.
Emphasise the importance of observing and recording what they see.

4. Observation and Explanation (10 minutes)

Explain evaporation: water will slowly disappear (evaporate) leaving the solid behind.
Ask students to observe the solution and discuss what might happen next.
Use questions to scaffold explanation: “Where does the water go?”, “What will happen to the salt/sugar?”
Introduce the words evaporation and crystallisation with visuals.

5. Reflection and Scientific Recording (10 minutes)

Have students write or draw their observations and thoughts about the process using the vocabulary list.
Encourage use of descriptive language: texture, shape, colour of crystals.
Discuss as a class what they observed and relate to their initial predictions.
Highlight how solids can dissolve, and as liquid evaporates, solids form crystals.

6. Next Steps and Daily Tracking (Right after the lesson)

Explain that the crystals will keep growing over several days as the water evaporates.
Organise a system for daily observations during the week where students add notes or drawings to their recording sheets.
Encourage students to compare their daily observations and update predictions accordingly.

Assessment & Feedback

Informal formative assessment through observation of students’ participation in discussions and their recorded predictions and observations.
Use success criteria as checkpoints during and after the lesson.
Provide feedback on use of scientific vocabulary and scientific thinking.
Encourage curiosity by asking open-ended questions: “What else could we try?”, “What other solids might crystallise?”

Differentiation

Provide sentence starters and visual support for prediction and observation recording.
Use paired learning for support.
Challenge interested students with further questions about the properties of crystals and why some solids dissolve and others don’t.

Teacher’s Reflection Prompts

Did students demonstrate understanding of solids, liquids, and dissolving?
Were students able to make logical predictions about evaporation and crystal growth?
How effectively did students use science vocabulary in their observations?
What adaptations may be needed for next time?

Additional Notes

Tie observations to real-world examples like salt flats, snowflakes, and rock candy to build curiosity.
Consider connecting with local Māori knowledge about crystals or minerals to enrich cultural relevance.
Use this experiment as a stepping stone to exploring other physical changes and mixtures in future lessons.

This structured approach aligns tightly with the NZ Curriculum’s science and key competencies for Year 3 students, ensuring a meaningful, hands-on, and language-rich exploration of crystals, solids, liquids, and dissolving processes that build foundational scientific literacy.

If you want, I can also help generate a printable student worksheet or prompt cards for vocabulary and observations to accompany this lesson!