Which Glue Will Be Strongest?

Overview

Students investigate which type of glue makes the strongest identical paper chain. They predict, make paper chains using the same size and number of paper strips, apply the same amount of different glues, allow the joins to dry for the same length of time, and gradually add paper clips or small weights until the first link breaks. They record evidence and use it to compare the glues in a fair test.

Learning intentions

Students will:

• make a prediction about which glue will make the strongest paper chain
• identify the independent, dependent and controlled variables in a fair test
• make identical paper chains using the same size and number of paper strips
• safely apply the same amount of different glues and allow joins to dry for the same length of time
• test each chain by gradually adding paper clips or small weights and count how many it holds before the first link breaks
• record, compare and explain results using evidence

Success criteria

• I can make a prediction and give a reason.
• I can explain that glue type is the independent variable and the number of paper clips held is the dependent variable.
• I can keep the paper-strip size, number of strips, glue amount, drying time and testing method the same.
• I can follow safety rules and test each chain gradually and carefully.
• I can record results in a table and use evidence to write a conclusion.

Curriculum links

• Science inquiry: suggesting and following safe procedures to test predictions.
• Science inquiry: sorting and ordering results in a table and identifying patterns.
• Science inquiry: comparing predictions, observations and findings from other groups, and suggesting further questions.
• Science understanding: exploring how materials can be physically changed by actions such as mixing, spreading, bending and breaking.

Vocabulary

material, mixture, PVA glue, flour paste, sand, bond, strength, prediction, evidence, fair test, observation, result, conclusion

Lesson structure (60 minutes)

1. 0–7 min · Hook and prediction. Show examples of paper chains made with different glues and ask, “Which glue will hold the most paper clips or small weights before the first link breaks?” Students record or draw a prediction and give a reason.

2. 7–15 min · Fair test and safety demonstration. Explain that the glue type is the independent variable and the number of paper clips held before the first link breaks is the dependent variable. The controlled variables are the paper-strip size, number of strips, amount of glue, drying time and testing method. Demonstrate making identical links, applying glue to the same joining area, allowing joins to dry, and adding one paper clip or small weight at a time. Reinforce: do not taste glue, keep glue away from eyes and mouths, wash hands after the investigation, use scissors and weights carefully, and tell an adult about spills or broken links.

3. 15–28 min · Make identical paper chains. In groups, students use the same size and number of paper strips for each chain. They make one chain for each glue type, apply the same measured amount of glue to each join, press joins together in the same way, label the chains and record the glue type. Teacher checks that the strips, glue amount and joining method are consistent.

4. 28–35 min · Drying and prediction check. Place the chains in a safe, labelled area to dry for the same length of time. If necessary, the teacher provides chains prepared earlier under the same conditions so testing can take place in the lesson. Students inspect the chains without pulling them and predict which chain will break first and why.

5. 35–48 min · Strength test. Teacher models hanging or attaching a container to one chain and adding one paper clip or small weight at a time. Students test each chain using the same method, adding weights gradually until the first link breaks. They stop immediately, count the paper clips or weights held, and record the result. Test each glue type in the same way and do not change the method between tests.

6. 48–56 min · Record and compare results. Students complete the results table, compare results with their predictions and discuss whether the test was fair. Ask: Which glue held the most? Which link broke first? Did all groups get the same result? What might have caused differences? Emphasise that conclusions should be based on the recorded evidence.

7. 56–60 min · Conclusion and cleanup. Students complete the conclusion frame: “The glue that held the most paper clips or weights was ____. Our evidence was ____. Our test was fair because ____. Our results might differ if ____.” Students return equipment, dispose of or store glue as instructed, clear paper scraps, wash hands and leave the area safe.

Resources

• the investigation slide deck
• prediction, results and conclusion sheets
• Different child-safe glues, clearly labelled
• Identical paper strips, pre-cut to the same size and with enough for the same number of links in each chain
• Measuring spoons, syringes or small cups for measuring equal glue amounts
• Rulers, pencils, scissors, glue spreaders and labels
• Paper clips or identical small weights
• Small containers, hooks or trays for adding weights safely
• Drying trays or labelled storage areas
• Table coverings, paper towels and handwashing supplies

Assessment

• Ask students to identify the independent variable, dependent variable and at least two controlled variables before testing.
• Check that groups use the same paper-strip size and number, measure the same amount of glue, allow equal drying time and use the same testing method.
• Observe safe handling of glue, paper clips or weights, and check predictions and completed results tables.
• Assess conclusions for a clear claim about glue strength supported by the number of paper clips or weights held, with an acknowledgement that results may vary.

Differentiation

• Support students with picture labels, a teacher-prepared method card on the step-by-step investigation sheet, sentence starters such as “I predict…” and “I observed…”, and adult support for measuring or recording.
• Pair EAL/D students with supportive peers and demonstrate vocabulary through the real materials, gestures and simple either/or questions.
• Provide larger strips, non-slip containers and a scribe or speech-to-text option for students with fine-motor, writing or access needs.
• Extend confident students by asking them to compare two repeated trials, identify the most likely source of error and suggest a new question, such as whether changing the amount or drying time affects strength.