Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 43 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) white paper (d) a small bowl
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
6. 6.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
7. 7.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) the iron setting
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
11. 11.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) white paper (d) a small bowl
14. 14.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
15. 15.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) putting the iron away
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
17. 17.⚖️ 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
18. 18.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a battery cell (d) yeast
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the iron setting (c) how dark the writing is
22. 22.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
23. 23.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
25. 25.True or false: plugging in the iron is a job a child can do. (a) True (b) False
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) the same cotton bud (d) how dark the writing is
27. 27.⚖️ 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) True (b) False
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
30. 30.True or false: plugging in the iron is a job for an adult. (a) True (b) False
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
32. 32.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
37. 37.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a balloon (d) white paper
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) ironing the paper

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