Matter, Mixtures & Water Properties — Investigation · Science 6: Matter, Energy & Earth Systems, Grade 6
How can particle models and measurements account for matter across changes? Which parts of a stated sand–salt–water mixture can a filter separate, and where does the matter go?
Separate a mixture and account for its matter
Investigate
Which parts of a stated sand–salt–water mixture can a filter separate, and where does the matter go?
Three 35–45-minute sessions: plan and predict; examine or collect evidence; explain, revise, and reflect. Use the complete supplied record when materials, time, access, or safe conditions are unavailable.
Materials
- The supplied stage record and labeled container drawings.
- Optional parent-approved clean sand/salt mixture, tap water, suitable filter, collecting cup, and spill tray.
- A notebook for substance, stage, observed appearance, and mass-account notes.
Before you begin
Do not taste samples, drink filtered liquid, mix unknown substances, or heat a closed vessel. Use supplied records for evaporation rather than boiling. Optional room-temperature drying takes longer than one lesson and should be supervised.
Plan separation and matter accounting
The model separates substances using particle size and solubility. Track one initial 30 g mixture across stages; do not add masses from different times as if they were independent samples. Treat actual incomplete recovery and balance resolution as evidence limits.
Method
- Draw the stated initial mixture: 20 g water, 4 g dissolved salt, and 6 g sand. Predict which material a suitable filter can trap.
- Explain the filter’s role using the particle-size and dissolution models. If an approved clean demonstration is used, record what is visible without calling it pure.
- Examine the supplied filtration record and identify where the sand remains, including material left on the filter.
- Use the supplied later residue record to track water entering the air and salt remaining. Optional room-temperature drying must have its own date and duration.
- Create a final destination account and check the 30 g total. Keep intermediate and final masses separate.
- Write a reasoned separation explanation and a limitation, then revise any claim that visible clarity proves safe water.
Supplied illustrative record — use when an actual test is unavailable
Illustrative classroom data authored for analysis, not measurements from a real learner, stream, product, or field study. Actual observations may differ; record them honestly and compare the methods.
| Stage or destination | Stated mass (g) | What the model includes |
|---|---|---|
| Initial mixture | 30 | 20 water + 4 salt + 6 sand |
| Filtrate after separation | 24 | 20 water + 4 dissolved salt |
| Dried collected sand | 5.5 | Sand removed and recovered |
| Sand retained on filter | 0.5 | Not in the recovered sand pile |
| Later salt residue | 4 | After water leaves the open liquid |
| Water transferred into air | 20 | Later destination in the idealized account |
Analyze and explain
- Why can the filtrate still contain salt although it looks clearer?
- Account for the final destinations without double-counting the intermediate filtrate.
- What explains incomplete sand recovery in this model?
- Why is this not a drinking-water certification?
What a strong explanation includes
- Correct particle/solubility explanation.
- A final account totaling 30 g without counting stages twice.
- Water and salt destinations distinguished.
- Recovery and measurement limitations identified.
- No claim that clarity or filtration alone establishes drinking safety.
Parent / teacher guide: discuss after the investigation
The supplied filter separates sand while dissolved salt remains with the water. The filtrate is therefore a 24 g solution, not pure water. Dissolution distributes salt particles at a scale that this model filter does not remove; it does not destroy the salt. The later residue of 4 g is consistent with the stated salt remaining after the 20 g water enters the surroundings. The final destination account is 5.5 g recovered sand + 0.5 g retained sand + 4 g salt + 20 g transferred water = 30 g. Adding the earlier 24 g filtrate to those final destinations would count some of the same matter twice. Stages in a process are successive records, not separate simultaneous piles to total indiscriminately. The 0.5 g sand left on the filter explains why the recovered pile is smaller than the initial sand amount in this model. Actual recovery could differ because of retained solution, spills, insufficient drying, or instrument limits. Record those conditions instead of declaring that missing measured mass has been destroyed. This demonstration studies separation and accounting; it does not test every dissolved chemical or microorganism, and a clear filtrate is not evidence that it is safe to drink. A stronger procedure would specify filter properties, collect residues carefully, and repeat the same mass-account method.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.