Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 970 · 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? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the iron setting (d) the same cotton bud
2. 2.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a cotton bud (d) a small bowl
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
5. 5.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a magnet (d) yeast
6. 6.⚖️ 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
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
8. 8.⚖️ 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
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) writing the message
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) plugging in the iron
12. 12.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) magnetic (d) physical
13. 13.True or false: reading the message is a job for an adult. (a) False (b) True
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
17. 17.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) plugging in the iron
18. 18.⚖️ 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
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) an adult with an iron (d) a cotton bud
21. 21.⚖️ 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 keep it the same (c) we change it
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
23. 23.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) a magnet (d) yeast
26. 26.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
27. 27.🧺 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) yeast (d) white paper
28. 28.🧺 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 cotton bud (d) turmeric powder
29. 29.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
30. 30.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Do we need yeast 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 iron setting”? (a) we keep it the same (b) we change it (c) we measure it
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) a small bowl
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids