Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 76 · 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.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
5. 5.⚖️ 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
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
7. 7.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) writing the message
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) yeast
11. 11.⚖️ 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
12. 12.⚖️ 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
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) an adult with an iron (d) lemon juice
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) a small bowl
17. 17.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a balloon (d) a magnet
20. 20.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
21. 21.True or false: writing the message is a job for an adult. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) yeast (d) turmeric powder
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
24. 24.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
25. 25.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
26. 26.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
30. 30.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) reading the message (d) letting the paper dry
34. 34.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (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.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
38. 38.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
39. 39.True or false: cutting the lemon is a job for an adult. (a) False (b) True
40. 40.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it

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