Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 725 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: putting the iron away is a job for an adult. (a) True (b) False
2. 2.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) white paper (d) a cotton bud
7. 7.True or false: letting the paper dry is a job a child can do. (a) False (b) True
8. 8.True or false: plugging in the iron is a job a child can do. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
10. 10.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) turmeric powder
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.True or false: white paper is needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a balloon (d) white paper
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a magnet (d) lemon juice
21. 21.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
22. 22.True or false: reading the message is a job a child can do. (a) True (b) False
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) an adult with an iron
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) lemon juice (d) a small bowl
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) yeast (d) a small bowl
27. 27.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
28. 28.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
29. 29.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
30. 30.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
32. 32.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
34. 34.True or false: cutting the lemon is a job for an adult. (a) True (b) False
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
37. 37.True or false: writing the message is a job for an adult. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the iron setting (d) how dark the writing is
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same paper (c) the ironing time (d) the kind of juice

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