Students can copy a science definition correctly without understanding the concept behind it.
They may be able to define density, erosion, or thermal conductivity well enough to complete an assignment. When they are asked to explain what the word means in a new situation, however, the definition may not be enough.
This is one reason I do not always want the textbook or vocabulary list to be students’ first encounter with a science concept.
Sometimes they need something to observe first.
A photograph, demonstration, specimen, short video, diagram, or familiar experience gives students something concrete to connect to the language and reading that follow. It begins building the background knowledge they will need to understand the science rather than simply copy information about it.
Students May Know More Than Their English Shows
When discussing background knowledge, it is important to distinguish between building knowledge and activating knowledge students already have.
Multilingual learners do not enter science classrooms without experiences or ideas about the natural world. They may understand a concept from another school, their home, their community, or something they have observed themselves. They may simply lack the English vocabulary needed to explain that knowledge in class.
A student may understand that different materials allow heat to move at different rates without knowing the term thermal conductivity. Another may have watched soil wash away during heavy rain without knowing the English word erosion.
A visual, demonstration, or discussion can help students connect what they already know to the academic language used in the lesson.
Other times, the concept or experience is genuinely new. In those cases, the teacher is building background knowledge that students can use when they begin reading.
Both matter.
Give Students Something to Think About Before They Read
I like to use images as an entry point into science.
One routine I have used begins with a highly magnified image. Shark skin, snake skin, pieces of a hornet’s nest, porcupine quills, bumblebees, and lice all look very different when magnified. The lice images always get a reaction.
I do not identify the image right away. Instead, I ask:
- What do you observe?
- What does that tell you?
- What do you think it is?
Students first describe what they can see. Then they consider what those details might mean. Finally, they make a prediction and support it with evidence from the image.
I narrow the possibilities based on their responses, and the class votes before I reveal the answer.
The activity only takes a few minutes, but now students have something to discuss. They have observed patterns, considered structures, made inferences, and used evidence before opening a textbook or copying a definition.
Background Knowledge Does Not Always Require a Mystery
The same idea works when students are not trying to identify an unknown object.
I have shown students an image of liquids with different densities and viscosities and asked why they think the liquids behave differently. Students begin by describing what they notice. Their observations give us a starting point for discussing the scientific concepts involved.
A teacher could also use:
- A photograph of erosion after a storm
- A short clip of an object changing speed
- A diagram with one important feature removed
- A graph showing an unexpected pattern
- A specimen or model
- A simple classroom demonstration
- Two images students can compare
The visual or phenomenon does not need to be elaborate. It needs to give students something relevant to notice and think about.
Why This Helps With Science Reading
Science texts often assume that students already understand more than they do.
A short passage may contain unfamiliar academic vocabulary, dense sentence structures, diagrams, labels, and references to processes students have never observed. For multilingual learners, the difficulty may come from both the science concept and the language used to explain it.
If students have already examined a relevant image or phenomenon, some of the text is no longer entirely abstract.
They can connect the reading to something they have seen:
- “That is the pattern from the image.”
- “That explains why the liquids formed layers.”
- “That word describes the structure we noticed.”
- “This is what caused the change we observed.”
The experience does not replace explicit instruction or careful reading. It gives students a place to attach the new information.
Where Vocabulary Fits
I do not think science teachers must choose between curiosity and explicit vocabulary instruction. Students need both.
Sometimes a few words must be introduced before students can participate in an observation or discussion. Words such as increase, decrease, layer, surface, and pattern may help students describe what they see.
More specialized terms may make greater sense after students have encountered the concept.
For example, students might first notice that one liquid remains above another. Once they have discussed the pattern, the terms density and viscosity help them name and explain what they observed.
Vocabulary is still taught directly. The difference is that the word is connected to an image, experience, or question instead of appearing as an isolated definition.
A Simple Sequence for Building Background Knowledge
A brief pre-reading routine might look like this:
- Show a relevant image, model, specimen, graph, or demonstration.
- Give students quiet time to observe before discussing.
- Ask what they notice.
- Ask what those details might suggest.
- Allow students to make a prediction or ask a question.
- Introduce the vocabulary needed to describe the concept.
- Read to confirm, revise, or extend the students’ thinking.
Students do not need to guess correctly. Their initial ideas give the class something to return to as they learn.
Support the Language Without Supplying the Thinking
Some students will have an idea but need help expressing it in English.
Simple sentence supports can help:
- I observe _____.
- I notice that _____.
- This detail suggests _____.
- I think _____ because _____.
- The image and the text both show _____.
- My thinking changed when I learned _____.
Students can also begin with a labeled sketch, a word, or a short phrase before developing a complete explanation.
The support provides a way into the discussion without telling students what to notice or what conclusion to reach.
Keep the Background Building Connected to the Lesson
An interesting image may capture attention, but attention alone is not the goal.
The image, video, or demonstration should prepare students for something they are about to read, discuss, model, or investigate. Otherwise, it can become an entertaining opening that has little connection to the actual learning.
Before choosing a background-building activity, I would ask:
- What will students need to understand in the upcoming text or lesson?
- What experience or visual could make that idea less abstract?
- Which vocabulary will help students discuss what they notice?
- How will we return to the opening activity later?
That final question matters. Returning to the original observation helps students recognize how their understanding has changed.
Final Thoughts
Building background knowledge does not require a separate lesson or an elaborate activity.
Sometimes it is a magnified image, three questions, and a class vote. Sometimes it is a graph, a short demonstration, or a connection to something students have already experienced.
The purpose is to give students enough context to make sense of the reading and vocabulary that follow.
Science does not have to start with the textbook.
It can start with something worth noticing.
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