Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 117 · 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.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
3. 3.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) writing the message
4. 4.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) reading the message
5. 5.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
8. 8.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
9. 9.True or false: reading the message is a job for an adult. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
11. 11.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
12. 12.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
13. 13.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
14. 14.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.True or false: white paper is needed for the secret lemon message. (a) False (b) True
17. 17.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) turmeric powder (d) white paper
19. 19.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) turmeric powder
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
24. 24.⚖️ 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
25. 25.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
26. 26.⚖️ 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) True (b) False
27. 27.⚖️ 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
28. 28.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) white paper (d) an adult with an iron
30. 30.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
34. 34.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
37. 37.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
38. 38.⚖️ 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
39. 39.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a mirror (d) a balloon

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