Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 667 · 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 of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) turmeric powder (d) a battery cell
2. 2.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) putting the iron away
3. 3.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a magnet (d) a cotton bud
5. 5.⚖️ 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
6. 6.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
8. 8.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
9. 9.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
10. 10.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) a cotton bud
12. 12.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
13. 13.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
14. 14.True or false: reading the message is a job for an adult. (a) True (b) False
15. 15.⚖️ 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
16. 16.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
17. 17.⚖️ 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
18. 18.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a magnet
20. 20.True or false: plugging in the iron is a job a child can do. (a) True (b) False
21. 21.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
22. 22.🔮 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
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) yeast (d) a mirror
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) turmeric powder
26. 26.⚖️ 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
27. 27.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ 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 measure it (c) we change it
29. 29.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) yeast (d) a battery cell
32. 32.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
33. 33.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
34. 34.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
35. 35.⚖️ 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) False (b) True
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
37. 37.⚖️ 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
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
40. 40.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message

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