Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 898 · 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? True or false: the same cotton bud is kept the same. (a) False (b) True
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
3. 3.⚖️ 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 same cotton bud
4. 4.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: plugging in the iron is a job for an adult. (a) False (b) True
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) an adult with an iron
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) reading the message (d) dipping the cotton bud
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) white paper (d) turmeric powder
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) lemon juice (c) white paper (d) a cotton bud
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
18. 18.🧺 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) lemon juice (d) yeast
19. 19.True or false: letting the paper dry is a job for an adult. (a) False (b) True
20. 20.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a magnet (d) an adult with an iron
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) writing the message
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
24. 24.True or false: plugging in the iron is a job a child can do. (a) False (b) True
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
26. 26.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
28. 28.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
30. 30.⚖️ 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
31. 31.True or false: putting the iron away is a job for an adult. (a) False (b) True
32. 32.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) ironing the paper (d) letting the paper dry
33. 33.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) putting the iron away
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
35. 35.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a balloon (d) turmeric powder
36. 36.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) lemon juice (d) a small bowl
38. 38.True or false: cutting the lemon is a job a child can do. (a) True (b) False
39. 39.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed

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