Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 158 · 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 battery cell for the secret lemon message? (a) not needed (b) needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) yeast (d) lemon juice
3. 3.⚖️ 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
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
5. 5.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a balloon
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
9. 9.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
10. 10.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
11. 11.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
12. 12.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
13. 13.⚖️ 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
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a small bowl
15. 15.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a magnet (d) a small bowl
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
20. 20.⚖️ 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 iron setting (c) how dark the writing is (d) the ironing time
21. 21.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
24. 24.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a balloon (d) a cotton bud
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper 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 the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
28. 28.True or false: ironing the paper is a job a child can do. (a) True (b) False
29. 29.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
31. 31.⚖️ 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
32. 32.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) white paper (d) turmeric powder
34. 34.🧺 Do we need an adult with an iron 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 battery cell (c) white paper (d) lemon juice
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
38. 38.True or false: white paper is needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False

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