Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 678 · 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.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ 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
3. 3.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
4. 4.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a mirror (d) a magnet
6. 6.True or false: cutting the lemon is a job for an adult. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.⚖️ 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 change it (c) we keep it the same
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
10. 10.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
12. 12.⚖️ 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 ironing time
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.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
16. 16.⚖️ 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) False (b) True
17. 17.🧺 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) a magnet
18. 18.True or false: letting the paper dry is a job for an adult. (a) True (b) False
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
20. 20.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
24. 24.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) lemon juice
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ 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
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
29. 29.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
30. 30.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ 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 measure it (c) we change it
33. 33.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a battery cell (c) a small bowl (d) a cotton bud
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
36. 36.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) dipping the cotton bud
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) white paper
38. 38.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
39. 39.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
40. 40.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown

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