Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 973 · 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.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
2. 2.True or false: letting the paper dry is a job a child can do. (a) True (b) False
3. 3.⚖️ 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 measure it (c) we keep it the same
4. 4.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
5. 5.🔮 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
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) a small bowl
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) white paper (d) a magnet
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) turmeric powder (d) yeast
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) a small bowl (d) lemon juice
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) putting the iron away
15. 15.True or false: reading the message is a job for an adult. (a) False (b) True
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a small bowl (d) lemon juice
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
20. 20.🧺 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 small bowl (d) yeast
21. 21.⚖️ 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
22. 22.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
23. 23.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
24. 24.⚖️ 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 keep it the same (c) we change it
25. 25.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ 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
29. 29.True or false: writing the message is a job a child can do. (a) True (b) False
30. 30.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
31. 31.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a small bowl (d) a cotton bud
33. 33.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a battery cell (d) a magnet
35. 35.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
36. 36.🛟 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
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the ironing time
38. 38.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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