Invisible Ink Experiment Worksheet

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

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