Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 873 · 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) dipping the cotton bud (c) writing the message (d) reading the message
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) an adult with an iron (d) yeast
3. 3.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a battery cell (d) white paper
5. 5.⚖️ 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
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
7. 7.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) ironing the paper
8. 8.True or false: ironing the paper is a job a child can do. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same paper
10. 10.⚖️ 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) False (b) True
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
12. 12.True or false: white paper is needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) white paper
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) putting the iron away
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
19. 19.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the ironing time (c) the same cotton bud (d) the kind of juice
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
22. 22.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a balloon (d) yeast
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
25. 25.True or false: cutting the lemon is a job for an adult. (a) False (b) True
26. 26.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
27. 27.🔮 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
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
31. 31.True or false: reading the message is a job a child can do. (a) False (b) True
32. 32.⚖️ 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
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: plugging in the iron is a job for an adult. (a) False (b) True
36. 36.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ 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
38. 38.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) plugging in the iron
40. 40.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True

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