Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 254 · 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 — ironing the paper? (a) a child can do it (b) an adult does it
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) an adult with an iron (d) a cotton bud
3. 3.⚖️ 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 ironing time (c) the kind of juice (d) the iron setting
4. 4.True or false: putting the iron away is a job for an adult. (a) True (b) False
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) how dark the writing is (c) the same paper
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a magnet (d) a cotton bud
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) turmeric powder (d) an adult with an iron
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a small bowl (d) an adult with an iron
12. 12.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
13. 13.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
14. 14.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
18. 18.⚖️ 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
19. 19.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) reading the message (d) writing the message
23. 23.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
26. 26.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
27. 27.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: putting the iron away is a job a child can do. (a) True (b) False
30. 30.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) reading the message (d) letting the paper dry
31. 31.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
34. 34.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) an adult with an iron
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
37. 37.⚖️ 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
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
39. 39.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
40. 40.⚖️ 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 keep it the same (c) we change it

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