Co-Teaching the Density Lab: Scaffold or Modify?
Ms. Brennan co-teaches sixth-grade science with Mr. Osei. Their next lab asks students to predict whether five objects float in salt water and explain why, using density. The class of 24 includes nine English learners: four at WIDA Level 4, three at Level 3, one at Level 2, and one Level 2 student with an IEP for a language-based learning disability. Students must read a two-page procedure, measure mass and volume, compute density, and write a claim-evidence-reasoning paragraph. Mr. Osei has one planning period a week with Ms. Brennan and has already printed the procedure, built a vocabulary list of 18 terms for students to define from the glossary before the lab, and planned to seat the ELs together at one table. Ms. Brennan is concerned that the 18-term list will consume an entire period and that the EL-only table will keep Level 2 students from hearing models of academic English. The lab is Thursday.
1. What is problematic about the 18-term glossary list and the EL-only grouping, and what would you substitute? Ground your reasoning in second-language acquisition principles.
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The glossary list fails on two grounds. Cognitively, 18 new terms in one lesson vastly exceed what working memory can hold; students will retain a handful and lose the rest. Pedagogically, defining words from a glossary is a dictionary-skill task that is itself difficult for a Level 2 reader - so the activity measures literacy under pressure, not science understanding. It also front-loads decontextualized labels before students have any experience to attach them to. Vocabulary sticks when it is attached to a referent.
Substitute: select five to seven high-utility terms - density, mass, volume, float, sink, predict, evidence. Teach three or four through experience first (two equal-volume objects of different mass in hand), then attach labels. Build a word wall during the lab rather than before it. Use cognates deliberately - densidad, masa, volumen, flotar - which give Spanish speakers free transfer.
The EL-only table fails differently. It removes students from model speakers of English and from grade-level science discourse, and it converts a heterogeneous group into a low track. What Level 2 students need is structured access to good models, not protection from them.
Substitute: heterogeneous groups of four with assigned roles - materials manager, measurer, recorder, reporter. Roles give the Level 2 student a defined contribution and a listening base; the Level 4 students get the productive challenge of explaining. Pair the Level 2 student with a patient, talkative partner - not with another Level 2 student, and not with the strongest student who will simply take over.
2. Write a language objective for this lab and explain what makes it usable - and how it differs from the content objective.
Read the worked answer
Content objective: Students will determine whether objects float by calculating and comparing density to the density of salt water.
Language objective: Students will explain whether an object will float by comparing densities, using the frame "The ___ is more/less dense than salt water, so it will ___."
Why this one is usable:
- It names a language function, not a topic. "Explain with cause" is something a student does; "learn vocabulary" is something a student is supposed to have happen to them.
- It specifies the forms the content demands. Comparatives plus a so result clause are exactly what a CER conclusion needs; students cannot write the conclusion without them.
- It is observable in the same task as the content. Ms. Brennan can listen to a group explanation or read a conclusion and score both objectives from one artifact.
Common failures to avoid:
- "Students will learn density vocabulary" - not measurable, not a function, and tells you nothing about what to look for.
- "Students will understand density" - that is a content objective in disguise.
- "Students will read the procedure" - a task, not an objective.
The pairing matters: the language objective exists because the content objective cannot be met without it. If the conclusion could be produced with a formula alone, the language objective would be decoration.
3. What specific supports would you build for the Level 2 student with the language-based IEP, and how do you avoid converting scaffolding into modification?
Read the worked answer
The distinction to hold: scaffolding changes how the student reaches the same standard; modification changes the standard. An accommodation removes a barrier; a modification removes a demand.
Appropriate scaffolds and accommodations:
- The procedure reformatted one step per line with a small image for each step - same content, lower reading load.
- The five essential terms pre-taught with realia the day before, plus cognate support if Spanish is her L1.
- A partially completed data table so the cognitive work is the measurement and the reasoning, not table construction.
- Oral rehearsal with a partner before writing the CER paragraph, plus a sentence frame or word bank.
- Speech-to-text or a scribe if the IEP documents writing as the barrier and writing fluency is not what the lab assesses.
- Extended time, per the IEP.
What to avoid:
- Reducing the number of objects or supplying the claim. That is modification - it changes what is measured and should be a team decision, documented, not an ad hoc Thursday-morning choice.
- Pulling her out during the lab for separate instruction. She needs the shared experience to have anything to write about.
Co-planning note: with one shared planning period a week, this cannot all be negotiated live. Mr. Osei and Ms. Brennan should agree on a standing division of labor - he designs the content and hands-on sequence; she designs the language supports and the CER frame - and use the weekly period to review student work against both objectives rather than to write materials from scratch.