Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 460 · 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.⚖️ 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
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) the ironing time (d) how dark the writing is
3. 3.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
5. 5.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
6. 6.True or false: cutting the lemon is a job a child can do. (a) False (b) True
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
8. 8.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
9. 9.⚖️ 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
10. 10.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) white paper (d) a cotton bud
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
13. 13.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a magnet
18. 18.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: ironing the paper is a job for an adult. (a) True (b) False
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
21. 21.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) letting the paper dry
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a battery cell (d) a mirror
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
25. 25.⚖️ 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
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
28. 28.True or false: white paper is needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a cotton bud
30. 30.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) writing the message
32. 32.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
33. 33.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away
34. 34.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) reading the message
35. 35.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
36. 36.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ 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 change it (c) we keep it the same
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it

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