Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 746 · 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.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
2. 2.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
3. 3.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
4. 4.⚖️ 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
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) lemon juice (d) a small bowl
7. 7.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a magnet (d) turmeric powder
8. 8.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) yeast (d) a battery cell
11. 11.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
12. 12.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a mirror
15. 15.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) writing the message
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a battery cell (d) a cotton bud
17. 17.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
18. 18.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
19. 19.True or false: writing the message is a job for an adult. (a) False (b) True
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
22. 22.⚖️ 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
23. 23.⚖️ 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 change it (c) we keep it the same
24. 24.True or false: letting the paper dry is a job for an adult. (a) True (b) False
25. 25.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the ironing time
30. 30.⚖️ 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) how dark the writing is (c) the same cotton bud
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) turmeric powder
32. 32.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
33. 33.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ 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) False (b) True
35. 35.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) putting the iron away (d) letting the paper dry
36. 36.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) writing the message
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
39. 39.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it

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