Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 934 · 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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
2. 2.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) turmeric powder (d) a mirror
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
4. 4.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
5. 5.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
6. 6.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
7. 7.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) writing the message
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a mirror (d) an adult with an iron
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) lemon juice (c) white paper (d) a small bowl
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) reading the message
11. 11.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
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.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
14. 14.True or false: plugging in the iron is a job for an adult. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
18. 18.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the same paper
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a battery cell (d) white paper
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) a balloon
24. 24.True or false: cutting the lemon is a job a child can do. (a) True (b) False
25. 25.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
26. 26.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
27. 27.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
28. 28.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
30. 30.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
31. 31.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) writing the message (d) dipping the cotton bud
32. 32.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) lemon juice (d) a cotton bud
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
36. 36.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
38. 38.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True

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